Fecal enrichment analysis is 10-15 times better than other methods in finding helminth eggs in feces. This is especially important for early diagnosis, because at the initial stage, helminthiasis is much easier to treat. For preventive purposes, donating stool using the enrichment method is recommended for everyone who is at risk.
What is a method?
Types of analysis and methodology
Kalantaryan enrichment method
Shulman enrichment method
Other methods
Berman's method for stool enrichment when taking a helminth test
Helps identify eel larvae in feces. For effective diagnosis, it is better to use still warm stool. The study uses a metal mesh with fine divisions placed in a glass funnel mounted on a stand. At the bottom of the funnel there is a rubber tube with a clamp. 5 grams of feces are placed in the mesh, lifted and warm water is poured into the funnel until the bottom of the mesh is submerged in water. Due to thermoactivity, helminth eggs slide towards warm water and accumulate at the bottom of the funnel. After 4 hours, the liquid is released and placed in a centrifuge for 3 minutes. The remaining sediment is subject to microscopic examination.
Enrichment method according to Krasilnikov
For the study, use a 1% solution of Lotus laundry detergent, in which feces are dissolved. When stirred, a suspension should form. The suspension is allowed to settle for 30 minutes and then placed in a centrifuge for 5 minutes. In a centrifuge, helminth eggs are cleared from feces and precipitate, which is examined under a microscope.
Preparation
- 2 days before the study, do not perform cleansing enemas, colonoscopy or x-rays of the stomach.
- The day before, do not eat fatty, smoked or fried foods.
- Within 3 days before the study, in the absence of contraindications, take a choleretic drug.
- The evening before the test, do not consume foods that change the color of feces.
- If possible, do not take antibiotics, iron supplements and sorbents.
Rules for collecting biomaterial for analysis:
- Before collection, thoroughly wash the external genitalia.
- Urinate beforehand.
- Collect feces in a special container.
- Take stool samples from 5 different places, in an amount of 3-5 ml.
- Make sure that urine and water do not get into the analysis.
- The sample for research must be submitted for diagnostics within the day of collection.
Indications
The use of a diagnostic technique is advisable when the following symptoms are detected:
- sudden change in stool (diarrhea gives way to constipation and vice versa);
- itching in the genital area;
- decreased appetite;
- increased irritability and poor sleep;
- constant feeling of hunger;
- dyspnea.
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Microscopic methods for diagnosing helminth infections, or why do you need a stool test for helminth eggs?
Patients often face questions about how to correctly take a stool test for helminth eggs, where to collect material for research, where and how to store it, and whether it is possible to say with confidence that there are no helminths if the result is negative. However, not all so simple.
It is almost impossible to determine the exact number of infected people in Russia, this is due to self-medication, lack of requests from the population for medical help and mass medical examination. The opinion of experts is that in Russia more than 20 million people are infected with helminths.
The active development of tourism, as well as increased migration, lead to the fact that the number of detected helminth species on the territory of the Russian Federation is progressively increasing, and species that are not typical for the territory of our country can often be found.
There are three groups that differ from each other in their distribution and development cycle.
Contact helminths (which have the simplest development cycle) do not require an intermediate host to transition from one stage to another; they release practically mature or mature eggs into the environment, which continue their development by landing directly on the body of their victim or on his clothing. The invasive form is the eggs themselves. A representative of this group is Enterobius vermicularis (pinworm) and others.
Geohelminths develop in the ground to the stage of larvae or mature eggs, do not require an intermediate host in their development, and enter the body of the final host through contaminated vegetables, or upon contact with contaminated soil. Representatives of this group: Trichocephalus trichiurus (whipworm), Ascaris lumbricoides (human roundworm), Ancylostoma duodenale (hookworm), etc.
A table comparing sources of infection, localization and laboratory diagnostic methods depending on the type of helminth is given below.
Table 1 - Laboratory diagnostic methods for different types of helminthic infestations
1. Laboratory diagnosis of helminth infections
Currently, the following methods are used to diagnose helminthiasis: macroscopic and microscopic (which are direct methods), serological diagnostic methods, PCR, ultrasound, x-ray methods, etc.
1.1. Macroscopy
The macroscopic method is an examination of the prepared material with the naked eye or with a magnifying glass. It is used before microscopy of the resulting substrate, intended to monitor the effectiveness of the treatment, as well as for differential diagnosis when parts of cestodes are detected. It is reliable when detecting segments of pork and bovine tapeworms, fragments of wide tapeworm, etc.
1.2. Microscopic research methods
Microscopic research methods make it possible to detect worm eggs (helminths) and larval forms in the original substrate. Feces, scrapings from perianal folds, sputum, pieces of muscle tissue, contents of the gallbladder, etc. can be used as material for microscopy. The laboratory diagnostic doctor, depending on the expected diagnosis, selects one or more microscopy methods.
The study of feces under a microscope in order to detect helminth eggs is called coproovoscopy (“kopros” - feces, “ovum” - egg, “skopeo” - I look). The study of material obtained from a patient under a microscope in order to identify helminth larvae in it is called larvoscopy (“larva” - larva).
1.3. Coproovoscopy (examination of stool for worm eggs)
Table 5 shows various modifications of coproovoscopy. The Kato-Miura method (examination of a thick smear of feces under cellophane) is the simplest and does not require significant effort or complex laboratory equipment. It is this method that is usually used in screening tests (for example, when a child enters a kindergarten, school, university, receives a medical book for decreed sections of the population, registers for sanatorium treatment or hospitalization, and so on).
If helminthiasis is suspected, in addition to the Kato-Miura method, the laboratory doctor always uses the so-called enrichment methods (sedimentation and flotation). The use of reagents for sedimentation or floating of helminth eggs facilitates their detection even with a low degree of invasion.
Table 2 - Ovoscopy methods
Quantitative methods of copro-ovoscopy are also used. These methods are used to determine the number of helminth eggs in 1 g of the test material, which makes it possible to approximately judge the degree of helminth infestation and the effectiveness of the treatment. Quantitative methods can be the thick smear method under cellophane according to Kato-Katz (modified by Kato and Miura) and the formaldehyde-ether and acetate-ether precipitation methods.
The information content of a single stool test for worm eggs is low, according to various estimates about 30-50%. This is quite enough to identify people with massive infestations during screening, but sometimes it is not enough to make a diagnosis. Therefore, if helminthiasis is suspected, the attending physician prescribes at least 3 studies with an interval of 7-10 days between them.
1.4. Coprolarvoscopy (examination of feces for helminth larvae)
1.5. Other methods of ovoscopy and larvoscopy
Microscopy of scrapings from the perianal area is widely used to detect pinworm (Enterobius vermicularis) and bovine tapeworm (Taeniarhynchus sagitanus) eggs. You can submit one of the scraping options directly to the laboratory or, having received the test tubes and spatulas necessary for the study, perform the scraping yourself at home and then submit the test material to the laboratory. We wrote about how to properly submit scrapings for enterobiasis in the corresponding article.
The effectiveness of all methods of scraping from perianal folds in diagnosing helminthiases is approximately the same; the choice of method depends on the availability of certain means for collecting a smear.
To diagnose helminthiases, microscopy of the contents of the duodenum is also used. It is advisable to deliver bile to the laboratory for research immediately after its collection. To detect Strongyloides stercoralis (intestinal acne), a native smear (without staining or treatment with any reagents) is used.
To detect trematode eggs (Opisthorchus felineus, Clonorchis sinensis, Fasciola hepatica, Dicrocoelium lancealum), the method of bile centrifugation followed by microscopy is used.
A biopsy of striated muscle tissue can be used to detect helminths (Trichinella). For study, a biopsy of the biceps or gastrocnemius muscles is used; microscopy is preferably performed immediately after collecting the material. Compression trichinoscopy and trichinoscopy using the method of artificial digestion in gastric juice are used.
To diagnose helminthiases, it is also possible to use a polymerase chain reaction, the substrate for which is blood, urine, feces, etc. Difficulties in using this method are associated with the small number of laboratories accredited to perform such tests. PCR allows you to detect helminth DNA in the test material, regardless of whether it is alive or not.
Based on the above, we see that for effective diagnosis of helminthiasis it is important to choose the right technique, because not all helminths can be detected by examining stool.
2. How to properly collect stool for analysis for helminth eggs?
Now let’s look at how to properly take a stool test for helminth eggs (for helminth eggs). No special preparation is required before taking this type of analysis. Stool after cleansing enemas, rectal suppositories, or the use of laxatives is not suitable for research.
Options for preparing the simplest preservative solutions for storing stool samples are given in the table below.
Distilled water 90.0 ml;
The resulting material can be stored in these preservatives for up to 2-3 weeks. To collect prepared feces in a preservative, the ratio should be observed: one part of feces to three parts of the selected preservative.
3. Rules for collecting scrapings from perianal folds
If you need to take a scraping from the perianal folds, this can be done at home or directly in the clinic. To obtain the material at home, you must first take from the clinic the necessary equipment for this (kits, spatulas, test tubes), you can use a cotton swab, which will be pre-moistened in warm water or saline solution (0.9% NaCl solution).
The procedure for collecting material is carried out in the morning immediately after waking up; before starting the manipulations there is no need to perform perineal hygiene, and there is no need to go to the toilet “in a big way”. Use a cotton swab to wipe the folds of skin around the anus. For reliability, material must be collected in several places at once. The finished material on a cotton swab is placed in a container or test tube and packed tightly. After collection, the material for research should be delivered to the laboratory within two hours. Don't forget to label the container. You can read more about modifications of the classic scraping for enterobiasis here.
The result of the material examination, as a rule, will be ready within one working day and you can receive an answer the very next day, but some laboratories may take longer to prepare the results.
If helminth eggs or their larvae are not found in the test material, then the result form will say: “No helminth eggs were found,” in other cases it will be written what type of helminth was found.
Therefore, it is important for patients to remember:
- 1 Standard stool analysis for helminth eggs is a good method for mass examination of the population, including decreed groups.
- 2 Not every helminthiasis can be recognized using a standard stool test for helminth eggs; therefore, if you suspect helminthic infestations, it is best to consult a doctor and not self-medicate.
- 3 The diagnostic method in each specific case is chosen by the doctor, based on the presence of certain symptoms of invasion.
- 4 The results of stool testing for helminth eggs directly depend on the correct collection of material. If you follow the above requirements, you will be much more likely to get the correct result.
- 5 If you receive the answer “No worm eggs were found,” there is a possibility that the result is false negative. In this case, the attending physician may recommend repeated studies at intervals of 7-14 days, as well as prescribe other diagnostic measures.
Distilled water 90.0 ml;
Distilled water 90.0 ml;
Detection of helminth eggs in feces using the enrichment method
The feces are suspended in a flotation solution, which has a higher relative density than helminth eggs. In this case, helminth eggs float to the surface, and the resulting film is examined under a microscope.
As a reagent, use a flotation solution according to Kalantaryan (1 kg of sodium nitrate is dissolved in 1 liter of water, boil the mixture until a film forms and pour without filtering into dry bottles; relative density of the solution is 1.38) or a flotation solution according to Brudastov - Krasnonos (900 g of nitrate sodium and 400 g of potassium nitrate are dissolved when heated in 1 liter of water; the relative density of the solution is 1.47-1.48).
Method for detecting helminth eggs in feces using the enrichment method
In beakers, thoroughly stir 5-10 g of feces and 100-200 ml of one of the flotation solutions with a glass rod. Immediately after the end of stirring, remove large particles that float to the surface with a glass rod. A glass slide is placed on the surface of the saline solution. If there is empty space between the mixture and the slide, add saline until the mixture comes into complete contact with the slide.
Leave to settle for 20-30 minutes, after which the slide is removed, placed under the microscope with the film facing up, and all the film adhering to the surface of the slide is examined without a cover glass. To avoid drying out during the study, the film can be mixed with two to three drops of a 50% glycerin solution.
All helminth eggs found in the preparation are taken into account.
The described method can detect infection with roundworms, whipworms, hookworms, taeniids, trematodes, tapeworms and other types of helminths.
Fecal analysis to determine eggs of various helminths
Such a study allows you to detect the presence of worms in the human body
When to take it?
The doctor prescribes a stool test for eggs of various helminths in the following cases:
Indications for the study are:
- Loose stools or diarrhea of unknown origin.
- Nausea, vomiting, abdominal pain.
- Diseases of the digestive system.
- Vulvovaginitis, itching in the perianal area.
- Urinary system infections.
- Weight loss, fatigue, poor appetite.
- For children - a lag in physical and psycho-emotional development.
What is the preparation?
No special preparation is needed. Before the study, the patient is advised not to eat foods rich in fiber, sorbents, medications or foods that affect the color of the stool. If the patient took antibiotics the day before, it makes sense to donate stool if helminths are suspected 7-10 days after they are discontinued.
Coprological studies in the diagnosis of helminthiasis are of great importance
How to properly submit stool for testing for protozoa and worm eggs?
- It is necessary to take the last, and not the first, portion of stool; it is better if it is liquid.
- Collect the material in special sterile containers intended for scatological research, purchased at any pharmacy.
- The sample must be delivered to the laboratory within the next 2-3 hours; if it takes longer, preservatives must be used.
How is stool analyzed for helminth eggs in the laboratory?
Analysis of stool for worm eggs is called helminthoovoscopy. It includes macroscopic and microscopic techniques that can be used sequentially.
Macroscopy
There is no risk of infection of laboratory personnel when using this method
Among these research methods there is also a method of settling - when feces are mixed with water and settled, after some time the upper part of the liquid is drained, adding new liquid to the original volume. As soon as the liquid becomes transparent, it is completely removed, and the sediment is carefully examined.
A smear is obtained by mixing stool with glycerin. With a small number of worm eggs in the preparation, they are not detected.
If the Kato method is used, a smear of feces is made on a glass slide, and the top is covered with cellophane film soaked in Kato solution, which contains phenol, glycerin and malachite green in the required proportions. This technique is more effective than studying native material.
The Shulman method is otherwise called the twisting method - the material is gently mixed without touching the inside of the vessel in a mixture of saline solution and water. The helminth eggs end up in the center. Next, use a glass rod to transfer a small amount of liquid onto the glass to prepare the drug.
Used to determine enterobiasis. The adhesive tape glued to a glass slide is examined under a microscope; the material is collected by applying it to the perianal folds.
Feces are mixed with water, filtered and left to stand for 30 minutes. The supernatant liquid is poured off. More liquid is added to the original volume, the material is shaken and settled again. Repeat until the top layer of liquid becomes transparent - a preparation is prepared from the sediment and examined under a microscope. They mainly look for trematode eggs using this method.
General analysis of stool (coprogram) includes macroscopic, chemical and microscopic examination
There are enrichment methods based on the difference in physical properties (specific gravity) of helminth eggs and the floating solutions used. These include:
- Formalin-ether or acetic sedimentation and its modifications.
The essence of sedimentation techniques is the sedimentation of helminth eggs in the chemical reagents used due to their greater specific gravity.
Fecal analysis for helminth eggs is carried out over several days. Stool samples are added to special containers with a formalin-based preservative (can be replaced with acetic acid) every day or at intervals of several days and stored for up to several weeks. After centrifugation, the settled part is examined under a microscope.
To search for vegetative forms or protozoan cysts, add Lugol's solution.
Lugol's solution - a preparation based on molecular iodine
Modifications of sedimentation methods using systems with ready-made reagents are possible.
Trematode eggs are well identified using these methods.
- Flotation (floating) methods: Kalantaryan, Fulleborn.
The role of a flotation solution can be performed by a saturated solution of table salt - the Fulleborn method (nematodes, tapeworms) or sodium nitrate - the Kalantaryan method (trematode eggs do not float). Ammonium nitrate may also be used.
It is based on the effect of detergents on the test material, during which helminth eggs are deposited. The detergent used as washing powder is completely dissolved in the material. Microscopy of the sediment is performed after centrifugation. This way you can identify all types of helminths.
The result and its features
You can take the test as prescribed by a doctor, having received a referral when visiting a clinic, or at your own request in a private laboratory. The choice of method for examining the material by the laboratory assistant will be based on what disease the doctor suspects and which worm eggs need to be found.
Microscopic examination is a more effective method than a native smear
- Subjectivity.
- The likelihood of a patient testing non-indicative stool for helminths.
- Delivery time to the laboratory is too long.
- Features of helminths, such as, for example, the phenomenon of “intermittent cyst excretion” in protozoa.
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Enrichment methods
1) concentration of eggs on the surface of the liquid (flotation, floating methods);
2) concentration of eggs in sediment (methods of precipitation, sedimentation).
Kalantaryan method (with flotation solution):
It is based on the fact that in a liquid with a high relative density, helminth eggs float to the surface as lighter ones, where they concentrate. For this, Kalantryan solution is used (1 kg of sodium nitrate is dissolved in 1 liter of water; the mixture is boiled until a film forms, cooled; the relative density of the solution is 1.38).
The eggs are left to float for 20-30 minutes, after which the slide is removed, placed under a microscope and viewed without a cover glass.
Fulleborn method:
The Fulleborn method allows one to examine a large amount of material and is widely used. Place 5 g of feces in a small jar (usually an ointment) and mix thoroughly with a 20-fold amount of saturated sodium chloride solution, adding it in small portions while stirring.
Since the eggs of trematodes and most cestodes float, it is necessary to examine the sediment from the bottom of the jar. Preparations from the sediment are not very transparent, so you can add a drop of glycerin to clarify.
Krasilnikov method (using detergents):
Under the influence of surfactants included in detergents (washing powders), helminth eggs are released from fecal matter and concentrated in the sediment.
Twisting method (according to Shulman):
The twisting method (according to Shulman) is very simple, more effective than the native smear method, but you cannot limit yourself to it when studying helminths.
It serves as a complement to egg and larval concentration methods.
Berman method:
The Berman method is used to identify helminth larvae (eels). Feces obtained from the patient (preferably freshly excreted) in an amount of 5 g are placed on a fine metal mesh (a milk strainer is convenient) in a glass funnel fixed in a tripod. A rubber tube with a clamp (Berman apparatus) is placed on the lower end of the funnel. The mesh (strainer) is lifted and water heated to 50 °C is poured into the funnel so that the lower part of the mesh is immersed in water.
Special methods are classified into the following types: 1. Magnetic and electrical enrichment; 2. Sorting; 3. Enrichment using the effects of interaction of pieces of separated components with the working surface of the separator; 4. Enrichment based on selectively targeted changes in the size of pieces of mineral components; 5. Enrichment based on the difference in the surface properties of the separated minerals.
1) Magnetic enrichment (magnetic separation) based on the use of differences in the magnetic properties of the components of the separated fur. mixtures with particle sizes up to 100, sometimes up to 150 mm in a non-uniform constant or variable magnetic field. field. The process is carried out in an aqueous or air environment in roller, drum, rotary and other magnets. separators. Magn. separation is widely used in the beneficiation of iron, manganese, copper-nickel ores and rare metal ores.
Electrical enrichment (electrical separation) based on differences in electrical St. Vakh components of fossil raw materials.
Drum electrostatic separator: 1-hopper for source material; 2-charged drum; 3-ci-lindrich. electrode; 4-drum cleaning device; 5-7 receivers resp. for non-conductors, semiconductors and conductors. 2) SORTING OF MINERAL RESOURCES. The main methods of sorting include: 1. Manual sorting (rock sampling, ore sorting, coal sorting). Manual sorting is used when mechanical or chemical enrichment cannot be used; when mechanical processes do not provide the required quality of separation, 2. Mechanized sorting, including processes with the general name radiometric enrichment methods. 3) ENRICHMENT USING THE EFFECTS OF INTERACTION OF PIECES OF SEPARATED COMPONENTS. 1. Enrichment in elasticity; 2. Friction enrichment; 3. Combined enrichment for friction and elasticity; 4.Enrichment in form; 5.Thermoadhesive enrichment method; 6. Enrichment on fatty surfaces. 4. Enrichment based on selectively targeted changes in the size of pieces of mineral components; 1. Selective crushing is applicable for minerals that have large aggregates of a valuable component that differ in strength from the host rocks. 2. Selective crushing - like selective crushing, takes advantage of differences in the strength of the components of the mineral. 3. Washing of minerals - used in the enrichment of loose deposits of rare and precious metals, ferrous metal ores (iron, manganese), phosphorites, kaolins, building materials (sand, crushed stone), fluxes, etc.
4. Attrition of minerals - used in the processing of glass sand, rock crystal, feldspar, chromite spar, chromite concentrates, artificial minerals, as well as in preparation for coal flotation. 5. Decripitation destruction - selective opening, based on the ability of individual minerals to collapse along cleavage planes when heated and subsequent rapid cooling or only when heated. 6. Thermochemical destruction - used for ores, the rock part of which is represented by carbonates, for example, calcite, magnesite, siderite, and the valuable component is represented by thermally stable minerals - pyrochlore, fluorapatite, etc. 7. Changing particle sizes using heat treatment - consists of heating the product being processed to the melting point of sulfur, forming an aqueous emulsion and then cooling it.
5)ENRICHMENT BASED ON THE DIFFERENCE IN SURFACE PROPERTIES OF SEPARATED MINERALS
Selective coagulation is the combination of particles of the dispersed phase into aggregates due to the cohesion (adhesion) of particles during their collisions.
Selective flocculation is a set of processes of selective aggregation of fine particles of minerals into microfloccules with a particle size of 100-300 microns using flocculant reagents of various natures.
Adhesive enrichment - this enrichment method is based on the selective adhesive interaction of the extracted component with a hydrophobic surface in water
Amalgamation is a method of extracting metals from ores by dissolving them in mercury. The amalgam is separated from the waste rock and the mercury is distilled off.
7. What is meant by the terms chemical and radiometric enrichment?
8. What is called enrichment by friction, decripitation?
9. What are the formulas for technological indicators of enrichment?
10. What is the formula for the degree of reduction?
11. How to calculate the degree of ore enrichment?
Seminar topics:
Main characteristics of enrichment methods.
Main differences from preparatory, auxiliary and main enrichment methods.
Brief description of the main enrichment methods.
Brief description of preparatory and auxiliary enrichment methods.
The degree of sample reduction is the main role of this method in mineral processing.
Homework:
Study the terms, rules and basic methods of enrichment, consolidate the acquired knowledge in a seminar lesson on your own.
LECTURE No. 3.
TYPES AND SCHEMES OF ENRICHMENT AND THEIR APPLICATION.
Purpose: To explain to students the main types and schemes of enrichment and the application of such schemes in production. Give an idea of the methods and processes of mineral processing.
Plan:
Methods and processes of mineral processing, their scope.
Concentrating factories and their industrial significance. Basic types of technological schemes.
Key words: main processes, auxiliary processes, preparatory methods, application of processes, diagram, technological scheme, quantitative, qualitative, qualitative-quantitative, water-sludge, apparatus circuit diagram.
1. At processing factories, minerals are subjected to successive processing processes, which, according to their purpose in the technological cycle of the factory, are divided into preparatory, processing and auxiliary.
For preparatory operations usually include crushing, grinding, screening and classification, i.e. processes that result in the disclosure of the mineral composition, suitable for their subsequent separation during the beneficiation process, as well as averaging operations of minerals, which can be carried out in mines, quarries, mines and processing plants. When crushing and grinding, a reduction in the size of pieces of ore and the opening of minerals is achieved as a result of the destruction of intergrowths of useful minerals with waste rock (or intergrowths of some valuable minerals with others). Screening and classification are used to separate mechanical mixtures obtained by crushing and grinding by size. The task of the preparatory processes is to bring mineral raw materials to the size necessary for subsequent enrichment.
To the main beneficiation operations include those physical and physico-chemical processes of separation of minerals, in which useful minerals are separated into concentrates, and waste rock into tailings. The main beneficiation processes include processes of separation of minerals according to physical and physico-chemical properties (shape, density, magnetic susceptibility, electrical conductivity, wettability, radioactivity, etc.): sorting, gravity, magnetic and electrical enrichment, flotation, radiometric enrichment, etc. As a result of the main processes, concentrates and tailings are obtained. The use of one or another beneficiation method depends on the mineralogical composition of the ore.
To auxiliary processes include procedures for removing moisture from enrichment products. Such processes are called dehydration, which is carried out to bring the moisture content of products to established standards.
At the processing plant, the feedstock during processing is subjected to a number of sequential technological operations. A graphical representation of the totality and sequence of these operations is also called technological scheme of enrichment.
When beneficiating minerals, differences in their physical and physicochemical properties are used, of which significant importance is color, shine, hardness, density, cleavage, fracture, etc.
Color minerals are varied . The difference in color is used in manual mining or sampling of coals and other types of processing.
Shine minerals is determined by the nature of their surfaces. The difference in gloss can be used, as in the previous case, for manual picking of ore from coals or sampling from coals and other types of processing.
Hardness minerals that make up minerals is important when choosing methods for crushing and beneficiation of certain ores, as well as coals.
Density minerals varies widely. The difference in density between useful minerals and waste rock is widely used in mineral processing.
Cleavage minerals lies in their ability to split from impacts in a strictly defined direction and form smooth surfaces along the split planes.
Kink has significant practical importance in beneficiation processes, since the nature of the surface of the mineral obtained by crushing and grinding has an impact during beneficiation by electrical and other methods.
2. Mineral processing technology consists of a series of sequential operations carried out at processing plants.
Processing plants are industrial enterprises in which mineral resources are processed using beneficiation methods and one or more commercial products with a high content of valuable components and a reduced content of harmful impurities are isolated from them. A modern processing plant is a highly mechanized enterprise with a complex technological scheme for processing minerals.
The set and sequence of operations to which ore is subjected during processing constitute enrichment schemes, which are usually depicted graphically
Technology system includes information about the sequence of technological operations for processing minerals at a processing plant.
Qualitative scheme contains information on the qualitative measurements of the mineral during its processing, as well as data on the mode of individual technological operations. Qualitative scheme(Fig. 1.) gives an idea of the adopted ore processing technology, the sequence of processes and operations to which ore is subjected during enrichment.
rice. 1. High-quality enrichment scheme
Quantitative scheme includes quantitative data on the distribution of minerals among individual technological operations and the yield of the resulting products.
Qualitative-quantitative scheme combines data from qualitative and quantitative enrichment schemes.
If the scheme contains data on the amount of water in individual operations and enrichment products, and on the amount of water added to the process, then the scheme is called slurry. The distribution of solids and water across operations and products is reported as a solid to liquid ratio S:L, such as S:L = 1:3, or as a percentage solid, such as 70% solid. The T:W ratio is numerically equal to the amount of water (m³) per 1 ton of solid. The amount of water added to individual operations is expressed in cubic meters per day or cubic meters per hour. Often these types of schemes are combined and then the scheme is called qualitative-quantitative slurry.
Introductory-sludge scheme contains data on the ratio of water and solids in enrichment products.
Device circuit diagram– a graphic representation of the path of movement of minerals and enrichment products through the apparatus. In such diagrams, devices, machines and vehicles are depicted conventionally and their number, type and size are indicated. The movement of products from unit to unit is indicated by arrows (see Fig. 2):
Rice. 2. Device circuit diagram:
1.9- bunker; 2, 5, 8, 10, 11 - conveyor; 3, 6 - screens;
4 - jaw crusher; 7 - cone crusher; 12 - classifier;
13 - mill; 14 - flotation machine; 15 - thickener; 16 - filter
The diagram in the figure shows in detail how the ore undergoes complete enrichment, including the preparatory and main enrichment processes.
Flotation, gravitational and magnetic enrichment methods are most often used as independent processes. Of two possible methods that give the same enrichment rates, the most economical and environmentally friendly method is usually chosen.
Conclusions:
Enrichment processes are divided into preparatory and basic auxiliary.
When beneficiating minerals, differences in their physical and physicochemical properties are used, of which color, shine, hardness, density, cleavage, fracture, etc. are essential.
The set and sequence of operations to which ore is subjected during processing constitute enrichment schemes, which are usually depicted graphically. Depending on the purpose, the schemes can be qualitative, quantitative, or slurry. In addition to the indicated diagrams, circuit diagrams of devices are usually drawn up.
A qualitative beneficiation scheme depicts the path of movement of ore and beneficiation products sequentially through operations, indicating some data on qualitative changes in ore and beneficiation products, for example, size. A qualitative scheme gives an idea of the stages of the process, the number of cleaning operations of concentrates and control cleaning of tailings, the type of process, the method of processing middlings and the number of final enrichment products.
If a qualitative diagram indicates the amount of ore processed, the products obtained in individual operations and the content of valuable components in them, then the scheme will already be called quantitative or qualitative-quantitative.
The set of diagrams gives us a complete understanding of the ongoing process of enrichment and processing of minerals.
Control questions:
1. What refers to the preparatory, main and auxiliary processes of enrichment?
2. What differences in mineral properties are used in mineral processing?
3. What are concentrating factories called? What are their uses?
4. What types of process flow diagrams do you know?
5. What is a circuit diagram of devices.
6. What does a quality process flow diagram mean?
7. How can you characterize the qualitative-quantitative enrichment scheme?
8. What does the water-slurry scheme mean?
9. What characteristics can be obtained by following technological schemes?
Beneficiation is the most important intermediate link between the extraction of minerals and the use of extracted substances.
Mineral beneficiation is a set of processes and methods for concentrating minerals during the primary processing of solid minerals. When processing minerals, it is possible to obtain both final marketable products (limestone, asbestos, graphite, etc.) and concentrates suitable for further technically possible and economically feasible chemical or metallurgical processing. The theory of mineral processing is based on the analysis of the properties of minerals and their interactions in separation processes - mineralurgy. Mineral beneficiation allows the use of complex and low-grade ores; reduce the cost of mining by using high-performance methods of continuous extraction from the massif, reduce transportation costs, because Often only concentrates are transported, and not the entire mass of extracted raw materials.
Mineral enrichment includes various methods for separating minerals by physical properties: strength, shape, density, magnetic susceptibility, electrical conductivity, wettability, adsorption capacity, surface activity, but without changing their aggregate-phase state, chemical composition, crystal chemical structure.
Processing of minerals at processing plants includes a number of sequential operations, as a result of which the separation of useful components from impurities is achieved. According to their purpose, mineral processing processes are divided into preparatory, main (concentration) and auxiliary (final).
All existing enrichment methods are based on differences in the physical or physicochemical properties of individual components of the mineral. There are, for example, gravitational, magnetic, electric, flotation, bacterial and other enrichment methods.
The direction was founded in the 60s of the 20th century by the deputy director of the Uralmekhanobr Institute for scientific affairs, corresponding member of the USSR Academy of Sciences Vladimir Revnivtsev.
Area of specialization:
- 1) development of technologies for the separation of ores and enrichment products of primary and placer deposits containing minerals of titanium, iron, zircon, copper, gold, noble and rare metals, tin, manganese, feldspar, quartz;
- 2) development of technologies for the enrichment of ferroalloy and aluminum production slags to obtain the metal component.
Work is carried out mainly on the basis of dry magnetic, electric and air separators. In some cases (for example, for placer deposits), gravity enrichment methods are used to obtain a collective concentrate followed by “dry” finishing. Completely dry circuits and installations are being developed for use in waterless areas.
Over 50 years of work in this field, scientists have accumulated valuable material and created several generations of unique and high-performance vertical electric separators. For example, one vertical electric separator can replace from 5 to 50 horizontal analogues, both domestic and imported.
Based on numerous scientific research data and the results of hundreds of industrial tests carried out at a number of mining and processing plants and deposits in the CIS countries, electrical separation everywhere confirms its versatility, efficiency and unlimited technological capabilities.
In addition, the use of dry enrichment methods in low temperature conditions creates the opportunity for year-round operation of mines in northern and waterless areas.
Special enrichment methods:
- - Manual ore sorting
- - Radiometric enrichment
- - Enrichment in friction and shape
- - Enrichment in elasticity
- - Thermoadhesive enrichment
- - Enrichment based on selective change in piece size
Ore dismantling
Manual sorting - manual selection of pieces of ore with a particle size of 25-300 mm, or waste rock, or harmful impurities from the ore mass being sorted. Ore sorting was carried out directly during underground mining, on old dumps, from the rock mass coming from the preparatory workings, as well as from the general ore mass at processing plants as the first processing operation.
Due to its high labor intensity, ore sorting is almost never used and has been widely replaced by mechanized separation processes (for example, radiometric enrichment, enrichment in heavy media). It is known to use ore sorting in artisanal methods of mining and processing raw materials, as well as in sorting precious stones (jewelry, cutting), incl. as finishing operations.
When sorting ores, they are guided by differences in shine, color and other external characteristics. The process of ore sorting is labor-intensive and increases with decreasing size of the separated material. To increase the efficiency of ore sorting, the contrast of the processed material is increased: washing the ore before sorting, separating small classes, uniform lighting, irradiation with UV rays, preliminary chemical. treatment. Ore sorting is carried out on a stationary sorting platform or on a table, as well as on a moving surface (belt and swing conveyors, ore sorting tables).
Radiometric enrichment
Radiometric enrichment of minerals is based on the natural (natural) radioactivity of ores, that is, the ability of minerals to emit, reflect or absorb radiation. Conventionally, radiometric enrichment also includes methods based on the interaction of any type of radiation with the substance of rocks and ores, from photons and nuclear particles (gamma and x-ray quanta, neutrons, etc.) to light, infrared radiation and radio waves.
Radiometric enrichment includes:
- 1) radiometric methods (called autoradiometric in enrichment), based on measuring the natural radioactivity of rocks and ores;
- 2) gamma methods (method of scattered gamma radiation, or gamma-electron method, or emission; gamma-neutron method, or photoneutron; method of nuclear gamma resonance, as well as X-ray radiometric method, if the primary method is photon or gamma radiation), based on the interaction of gamma or x-ray quanta or atoms of elements that make up rocks and ores;
- 3) neutron methods (neutron absorption, neutron resonance, neutron gamma method and neutron activation method), based on the effects of interaction of neutron radiation with the nuclei of elements composing rocks and ores;
- 4) methods based on the interaction of non-radioactive radiation with minerals and rocks, incl. photometric, radio wave, radio resonance (this group conventionally includes luminescent and x-ray luminescent methods).
The dividing signs for radiometric enrichment are the spectral composition and intensity of primary or secondary emissions arising in the process of such interactions. The effectiveness of using a particular radiometric enrichment method depends on many factors, including from the physical methods, methods and hardware and technical means of its implementation, from the properties of the ore (contrast) and the processed raw materials, the assigned mining technological tasks and the stages of ore preparation.
Radiometric enrichment methods are used at mining enterprises: at the stage of detailed and operational exploration of deposits for technological mapping of ores; delineation of ore bodies; assessing the content of useful components in them in order to obtain initial data for calculating reserves and managing the process of extracting ore from the subsoil; at the stage of explosive breaking for preliminary concentration of p.i. by clarifying the contours of the explosion and the order of work; for preliminary sorting of marketable ores in bulk, transport containers (cars, dump trucks, trolleys) and streams (conveyor belts) after large and medium crushing; for lump separation of ores after medium and fine crushing; to control the technological process at enrichment plants through express analysis of feedstock and enrichment products (tailings, feed, concentrates, middlings, etc.).
Radiometric enrichment allows you to control the quality of ores (ore preparation systems) due to high productivity and accuracy that meets production requirements, as well as the ability to automate labor-intensive processes. The most effective are ore preparation systems in which radiometric enrichment methods are used at all stages of the technological process of ore mining and processing, from the conditions of the natural occurrence of ores to the control of the final products of the enterprise and production waste, for example. at mining enterprises mining and processing radioactive ores. Work is underway to create similar systems at deposits of non-ferrous, ferrous and rare metal ores, as well as non-metallic raw materials.
Enrichment in friction and shape
Enrichment in friction and shape is based on the use of differences in the speed of movement of separated particles along a plane under the influence of gravity.
The speed of movement of particles along an inclined plane (at a given angle of inclination) depends on the state of the surface of the particles themselves, their shape, humidity, density, size, properties of the surface on which they move, the nature of the movement (rolling or sliding), as well as the environment in which separation occurs.
The main parameter characterizing mineral particles from the point of view of their movement along an inclined plane is the friction coefficient.
The magnitude of the friction coefficient is determined mainly by the shape of the mineral particles, which, in turn, depends on the nature of the deposit (placer or bedrock). Mineral particles of placer deposits, as a rule, are spherical, while bedrock particles have an irregular (plate-like) shape (fragments).
Friction enrichment will be more favorable, the greater the difference in the aspect ratio for waste rock particles and useful minerals. The coefficient of friction increases with decreasing particle size, so efficient separation requires a narrow classification of material by size. Typically, friction enrichment is used for material with a particle size of 100 - 10 (12) mm.
Example: Differences in the shape of the grains and the coefficient of friction make it possible to separate flat, scaly mica particles or fibrous asbestos aggregates from rock particles that have a rounded shape. When moving along an inclined plane, fibrous and flat particles slide, and rounded grains roll down. The rolling friction coefficient is always less than the sliding friction coefficient, so flat and round particles move along an inclined plane at different speeds and along different trajectories, which creates conditions for their separation.
Enrichment by elasticity
Enrichment by elasticity is based on the difference in trajectories along which mineral particles having different elasticity are thrown when falling onto a plane. The elasticity of minerals is judged by the ratio h: H, where h is the height of reflection of a particle dropped from a height H onto a horizontal glass plate.
Speed recovery coefficient K 2 =h/H. Minerals, having different values of the coefficient K, will move along different trajectories, which makes it possible to separate them from each other. Separation of particles by elasticity is used in the enrichment of building materials (crushed stone and gravel for the production of high-grade concrete). To enrich gravel by elasticity, separators with an inclined steel plate are sometimes used. Falling onto the slab, more elastic particles are reflected at a greater angle with greater speed, while less elastic and fragile particles are reflected slightly and fall into the corresponding receivers.
Thermoadhesive enrichment
With thermoadhesive enrichment use preheating of the material (for example, using infrared lamps) and a transport tape coated with thermoplastic polymer material or paraffin. In this case, particles of different material composition are heated differently, as a result of which they plasticize the heat-sensitive layer on the tape underneath them in different ways. It is in this way that sulfide-containing, graphite, chromite, tourmaline and other materials that are “opaque” and relatively hot are temporarily adhesively fixed to the tape. “Unheated” coarse-crystalline materials (such as halite, sylvite, cryolite, fluorite, quartzite, calcite) are removed from the moving belt freely.
Enrichment based on selective change in piece size
A number of rocks have the property of contrasting changes in the sizes of their constituent components upon destruction. When these rocks are destroyed (for example, crushed), not only does opening occur (i.e., separation of the grains of the components forming the rock), but at the same time the particle sizes of the useful component turn out to be significantly different from the particle sizes of other components (waste rock). For such rocks, enrichment can be reduced to separation by particle size. The size of particles becomes an indirect sign of their material composition.
Selective crushing is applicable for minerals that have large aggregates of a valuable component that differ in strength from the host rocks. Such minerals include coal, brown iron ores, KMA iron ores, asbestos-containing ores, potash ores and some others.
The most widespread in the practice of coal processing are semi-rigid crushers (drum crushers). They have technical characteristics: diameter - 2.2-3.5 m; drum length - 2.8-5.6 m; speed - 10-16 per minute; productivity 130-160 t/h.
The main directions for the development of mineral processing: improvement of individual processing processes and the use of combined schemes in order to maximize the quality of concentrates and extract useful components from ores; increasing the productivity of individual enterprises by intensifying processes and enlarging equipment; increasing the complexity of the use of minerals with the extraction of valuable components from them and waste disposal (most often for the production of building materials); production automation.
One of the important tasks is to minimize environmental pollution through the use of recycled water and the wider use of dry enrichment methods.
The scale of use of mineral resources is continuously increasing, and the quality of ores is systematically deteriorating. The content of useful minerals in ores decreases, their enrichment deteriorates, and the ash content of coal increases. All this predetermines a further increase in the role of mineral processing in industry.
environmental enrichment fossil
Bibliography
- 1. Derkach V.G. Special methods of mineral processing. M: Nedra Publishing House, 1966. 338 p.
- 2. Mining encyclopedia. - M.: Soviet Encyclopedia. Edited by E.A. Kozlovsky. 1984-1991.
- 3. Mokrousov B.A., Golbek G.P., Arkhipov O.A., Theoretical foundations of radiometric enrichment of radioactive ores, M., 1968;
- 4. Mokrousov V.A., Lileev V.A., Radiometric enrichment of non-radioactive ores, M., 1979;
- 5. Arkhipov O.A., Radiometric dressing of ores during their exploration, M., 1985.
- 6. Kravets B.N. Special and combined methods of enrichment: Textbook for universities. M: Nedra Publishing House, 1984. 304 p.
2Screening is the process of separating lump and granular materials into products of different sizes, called classes, using screening surfaces with calibrated holes (grids, sheet and wire sieves).
As a result of screening, the source material is divided into an over-sieve (upper) product, the grains (pieces) of which are larger than the size of the holes of the sifting surface, and an under-sieve (lower product), the grains (pieces) of which are smaller than the size of the holes of the sifting surface.
Crushing and grinding – the process of destruction of minerals under the influence of external forces to a given size, the required granulometric composition or the required degree of disclosure of materials. When crushing and grinding, over-grinding of materials should not be allowed, as this impairs the process of mineral enrichment.
Classification – the process of separating a mixture of mineral grains into classes of different sizes according to the rates of their deposition in aqueous or air environments. Classification is carried out in special devices called classifiers, if the separation occurs in an aquatic environment (hydroclassification), and by air separators, if the separation occurs in an air environment.
Gravitational processes enrichment refers to enrichment processes in which the separation of mineral particles differing in density, size or shape is due to differences in the nature and speed of their movement in the environment under the influence of gravity and resistance forces.
Gravity processes include jigging, enrichment in heavy media, concentration on tables, enrichment in sluices, chutes, jet concentrators, cone, screw and counterflow separators, pneumatic enrichment.
Flotation enrichment methods – the process of separating finely ground minerals, carried out in an aqueous environment and based on the difference in their ability, natural or artificially created, to be wetted by water, which determines the selective adhesion of mineral particles to the interface between two phases. A major role in flotation is played by flotation reagents - substances that allow the process to proceed without any special complications and accelerate the flotation process itself, as well as the yield of the concentrate.
Magnetic enrichment methods minerals are based on the difference in the magnetic properties of the separated minerals. Separation based on magnetic properties is carried out in magnetic fields.
During magnetic enrichment, only non-uniform magnetic fields are used. Such fields are created by the appropriate shape and arrangement of the poles of the magnetic system of the separator. Thus, magnetic enrichment is carried out in special magnetic separators.
Electric enrichment is the process of separating minerals in an electric field, based on the difference in their electrical properties. These properties are electrical conductivity, dielectric constant, triboelectric effect.
3.Manual mining and rock sampling as a method of enrichment are based on the use of differences in the external characteristics of the separated minerals - color, shine, shape of grains. From the total mass of the mineral, the material that is contained in less is usually selected. In the case when a valuable component is selected from a mineral, the operation is called mining, when waste rock is called rock mining.
Decripitation is based on the ability of individual minerals to crack (destroy) when heated and subsequent rapid cooling.
Enrichment in friction, shape and elasticity is based on the use of differences in the speed of movement of separated particles along a plane under the influence of gravity. The main parameter of the movement of particles along an inclined plane is the friction coefficient, which depends mainly on the nature of the surface of the particles themselves and their shape.
Adiometric sorting , based on differences in the radioactive properties of minerals or the strength of their radiation
Radiometric enrichment methods based on the different abilities of minerals to emit, reflect, or absorb different types of radiation.
To chemical enrichment methods include processes associated with the chemical transformations of minerals (or only their surface) into other chemical compounds, as a result of which their properties change, or with the transfer of minerals from one state to another.
Chemical and bacterial enrichment based on the ability of minerals, such as sulfides, to oxidize and dissolve in highly acidic solutions. In this case, the metals go into solution, from which they are extracted using various chemical and metallurgical methods. The presence of certain types of bacteria, such as thionic bacteria, in solutions significantly intensifies the process of dissolution of minerals.
In technological schemes for the enrichment of complex complex ores, two or three different enrichment methods are often used simultaneously, for example: gravity and flotation, gravity and magnetic, etc. Combined enrichment methods in combination with hydrometallurgical ones are also used.
For the successful application of one or another enrichment method, the minerals must have sufficient differences in the properties that are used in this method.
4. The beneficiation process is characterized by the following technological indicators: metal content in the ore or beneficiation product; product yield; degree of reduction and metal recovery.
Metal content in ore or beneficiation product - this is the ratio of the mass of this metal in the ore or enrichment product to the mass of dry ore or product, expressed as a percentage. The metal content is usually denoted by the Greek letters α (in the original ore), β (in the concentrate) and θ (in the tailings). Precious metal content is usually expressed in units of mass (g/t).
Product yield - the ratio of the mass of the product obtained during enrichment to the mass of the processed original ore, expressed in fractions of a unit or percentage. The concentrate yield (γ) shows what proportion of the total ore is concentrated.
Degree of reduction - a value indicating how many times the yield of the resulting concentrate is less than the amount of processed ore. Degree of reduction (TO) expresses the number of tons; ore that needs to be processed to obtain 1 ton of concentrate, and is calculated by the formula:
K= 100/γ
Ores of non-ferrous and rare metals are characterized by a low yield of concentrate and, consequently, a high degree of reduction. The concentrate yield is determined by direct weighing or according to chemical analysis using the formula:
γ =(α - θ/β - θ)100,%.
The degree of enrichment, or the degree of concentration, shows how many times the metal content in the concentrate has increased compared to the metal content in the ore. When enriching poor ores, this figure can be 1000... 10000.
Metal recoveryε - is the ratio of the mass of metal in the concentrate to the mass of metal in the original ore, expressed as a percentage
ε=γβ/α
Metal Balance Equation
εα=γβ
connects the main technological indicators of the process and allows you to calculate the degree of metal extraction into concentrate, which, in turn, shows the completeness of the transition of metal from ore to concentrate.
The yield of enrichment products can be determined from chemical analyzes of the products. If we designate: - concentrate yield; - metal content in ore; - metal content in the concentrate; - metal content in tailings, and - extraction of metal into concentrate, then it is possible to draw up a balance of metal for ore and enrichment products, i.e. the amount of metal in ore is equal to the sum of its quantities in concentrate and tailings
Here, the yield of the original ore in percent is taken as 100. Hence the output of the concentrate
Metal recovery into concentrate can be calculated using the formula
If the concentrate yield is unknown, then
For example, when beneficiating lead ore containing 2.5% lead, a concentrate containing 55% lead and tailings containing 0.25% lead were obtained. Substituting the results of chemical analyzes into the above formulas, we get:
concentrate yield
extraction into concentrate
tailings exit
degree of enrichment:
Qualitative and quantitative enrichment indicators characterize the technical perfection of the technological process at the factory.
The quality of the final enrichment products must meet the requirements set by consumers for their chemical composition. Requirements for the quality of concentrates are called standards and are regulated by GOST, technical conditions (TU) or temporary standards and are developed taking into account the technology and economics of processing of this raw material and its properties. The standards establish the minimum or maximum permissible content of various mineral components in the final enrichment products. If the quality of the products meets the standards, then these products are called standard.
Conclusions:
The processing plant is an intermediate link between the mine (mine) and the metallurgical plant. Ore of various sizes coming from the mine, when processed at the processing plant, undergoes various processes, which, according to their purpose, can be divided into preparatory, processing and auxiliary.
Preparatory processes aim to prepare the ore for beneficiation. Preparation includes, first of all, operations of reducing the size of ore pieces - crushing and grinding and the associated classification of ore on screens, classifiers and hydrocyclones. The final grinding size is determined by the size of mineral dissemination, since during grinding it is necessary to open the grains of valuable minerals as much as possible.
The beneficiation processes themselves include the processes of separating ore and other products according to the physical and physico-chemical properties of the minerals included in their composition. These processes include gravitational enrichment, flotation, magnetic and electrical separation, etc.
Most enrichment processes are carried out in water and the resulting products contain large amounts of it. Therefore, there is a need for auxiliary processes. These include dehydration of enrichment products, including thickening, filtration and drying.
In addition, there are so-called special enrichment methods, which include:
mining based on the difference in color and luster of individual minerals, their transparency or glow;
adiometric sorting, based on the difference in the radioactive properties of minerals or the strength of their radiation;
friction enrichment, based on the difference in the friction coefficients of minerals when they move along a plane;
chemical and bacterial enrichment based on the ability of minerals, such as sulfides, to oxidize and dissolve in highly acidic solutions.
The beneficiation process is characterized by technological indicators: metal content in the ore or beneficiation product; product yield; the degree of reduction and extraction of metal, which determines the main characteristics of the enrichment processes.
Control questions:
1.
What sections are mineral processing methods divided into?
2.
Which methods are considered primary and which are auxiliary methods of enrichment?
3.
What enrichment methods do you know?
4.
Describe the processes of screening, crushing, grinding and classification.
