Magnetic separator
PTMS magnetic separation
what is magnetic separation method ?
Kaolin is an important mineral in the industry and has many uses. Improving purity (whiteness) is an important task in the processing of kaolin clay. So what are the kaolin purification equipment? How to improve the purity of kaolin?
Kaolin purification and purification equipment
Nowadays, high-quality resources are rapidly reduced, and the demand for kaolin in industrial high-tech applications is increasing. Kaolin mineral processing and purification are becoming more and more important in processing.
The beneficiation method of kaolin is determined according to the type of impurities to be removed, micro-inlay size and product quality standards.
In general, you need to consider the following aspects:
For kaolin, which contains less impurities, higher whiteness, less titanium and iron impurities, the main impurity is sand (quartz, feldspar, etc.). The kaolin is simply crushed by air separation and classification method (ie dry beneficiation). ).
The content of impurities is high, the whiteness is low, and the kaolin with high sandy minerals and mineral content is generally used for re-selection of sand removal. Use magnetic separation of magnetic separators or magnetic separation of high gradient separators (except iron and titanium minerals), chemical bleaching (except iron ore to reduce ferric iron by ferric iron). Flotation (including aluminum ore, alumite separation or removal of anatase).
Soft kaolin and sandy kaolin are generally wet-processed.
The main process is as follows
Raw ore: storage or mixing, pulping, removal of plant fibers, grading, sand removal, magnetic separation, bleaching, pressure filtration, dehydration, drying.
The beneficiation process of soft kaolin and sandy kaolin is relatively simple.
After the precipitate is mixed, water and a dispersing agent are added to the agitator or the tamper according to the set concentration requirements. The role of the slurry is to disperse the kaolin, separate it from the sandy minerals and plant fibers, and prepare a suitable slurry for the next step of removing impurities and sand.
The prepared pulp is removed from the plant fiber and the coarse-grained sand by a vibrating sieve, and then the fine-grained sand is removed by a hydrocyclone and a horizontal screw unloading Cuikang centrifugal classifier.
If the product after sand removal can meet the requirements of certain application fields, flocculant (such as alum) can be added for coagulation, and then the filtration pressure is dried.
If high quality or high quality kaolin is required, strong magnetic separation or high gradient magnetic separation and chemical bleaching are also required.
For high-purity, high-purity kaolinite or kaolinite, after the ore is crushed, it can be ground and classified according to the requirements of the application field.
The ore containing a small amount of sand can be subjected to dry and wet classification after being ground to an appropriate fineness.
The ore with high iron content can be magnetically separated.
If the micro-chimera containing iron ore has a coarse particle size, coarse-grained (less than 74) can be subjected to dry magnetic separation.
However, if the grain size of iron is fine, wet magnetic separation or high gradient magnetic separation should be performed after fine grinding.
If high quality kaolin products are not satisfactory after magnetic separation, fine particle flotation, selective flocculation and chemical bleaching can also be employed.
At present, the crushing and screening equipment commonly used for hard kaolin or kaolin is a jaw crusher, a roller-type crusher, a vibrating screen, and the like. The grinding equipment mainly includes a suspension roller mill (lammon mill), a pressure roller mill, a mechanical impact mill, a ball mill and the like.
The dry sand removal equipment mainly includes an air centrifugal classifier (selection type) and a wet classifier, and mainly has a swirling unit and a horizontal screw discharge sedimentation centrifuge.
Flotation method
Selective flocculation: Selective flocculation is the use of different organic minerals on the surface physicochemical properties, the preferential adsorption of a component surface by an organic polymer selective flocculant, and then through the long-line polymer flocculant The "bridge" function, the particles of the component are flocculated into a mass, while the particles of other components can still be suspended and dispersed in the slurry, so that the floc and the suspended particles can be conveniently and effectively separated directly or indirectly.
The floc and suspended particles can be directly or indirectly separated directly or indirectly.
The process of selective flocculation is relatively simple.
First, the solid particles in the suspension are completely dispersed, and then the target mineral (mineral particles or coal gangue fine mud) is selectively adsorbed by adding a flocculating agent.
Abstract After flocculation of the target mineral, the flocculant is separated from the dispersed phase by flotation.
Circulating carrier flotation: Carrier flotation is the use of ore particles of general flotation particles as a carrier, so that the target mineral fine particles cover the carrier flotation.
Kaolin equipment purification
The impurities of colored minerals in kaolin, such as iron ore, pyrite, lignite, hematite, redstone, etc., all have weak magnetic properties.
Therefore, kaolin after sand removal usually requires magnetic separation.
Since the iron and titanium ore of kaolin are mostly micro-combined, the removal rate of strong magnetic separation is generally not high.
Therefore, most high gradient magnetic separators are used in industry for kaolin magnetic separation.
High gradient magnetic separation refers to the high magnetic gradient (ie, high magnetic force) of a small magnetic medium surface selected under a high background magnetic field, thereby achieving the purpose of magnetic separation, which cannot be achieved by general magnetic separation.
This method has two characteristics.
First, it has a polymagnetic medium (usually steel wool) that produces a high-intensity magnetic field.
Second, there are advanced screw magnetic structures.
High gradient magnetic separation technology has a very effective effect in removing weak magnetic fine particles or even colloidal particles from useful minerals.
In high gradient and strong magnetic field concentrators, the harmful impurities of titanium are easier to remove than iron.
In addition, a better superconducting magnetic separator is also used to separate and remove iron from kaolin.
The magnetic separator not only further increases the magnetic field strength, but also obtains high quality high quality kaolin with low energy consumption and small footprint.
Low-temperature superconducting magnetic separation equipment is mainly used for mineral enrichment purification and impurity removal, magnetic mineral resources and tailings disposal, etc. Through industrial tests, the equipment has achieved good results in the kaolin iron separation test, the raw ore Fe2O3 content 1.4 - 4%, through the content of magnetic concentrate Fe2O3 can be reduced by less than 0.9%.
Compared with traditional magnetic separation equipment, the company's self-developed low-temperature superconducting magnetic separation technology has the following characteristics:
Low energy consumption, energy saving, and reduced consumption are very significant benefits, and energy efficiency is as high as 90% compared with the same magnetic separation specification;
Such a carrier can be carried by the same mineral or a different kind of mineral.
Abstract The principle of two-fluid flotation is to use the difference of interfacial tension between solid (mineral), liquid (water) and oil, the difference of interfacial tension between different ore particles at the three-phase boundary, and the different mineral grains in the three-phase interface. Poor hydrophobicity.
The selective enrichment of ore particles in the oil-water interface is the theoretical basis of two-liquid flotation.
By adding a collector, you can adjust the wettability and interfacial tension of the mineral surface, enrich the fine minerals at the oil-water interface, or extract the ore particles into the organic phase.
Chemical purification bleaching
The chemical treatment of kaolin is often associated with the performance of the kaolin and the impurities contained therein. The main impurities affecting the performance of kaolin and coal-based kaolinite are iron minerals, titanium minerals and organic matter. Alkali treatment often does not have much effect. The common chemical treatment methods for impurity removal and purification are acidification and chemical bleaching. law. Acid treatment and chemical bleaching can also be regarded as two aspects of a method or two stages of a complete process. The two are closely related. The difference is that the acid treatment is mainly for the purpose of removing impurities. Bleaching is the main purpose of changing the valence state of the coloring element (mainly iron) and reducing its color rendering. In fact, the acid leaching process often adds an oxidizing agent or a reducing agent to achieve the above purpose.
Sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, oxalic acid, phosphoric acid, etc. are often used in the acid leaching of kaolin. They can react with hematite, limonite and siderite in kaolinite (soil) to form soluble. salt. After the soluble salt is formed, the iron-containing solution and the relatively pure kaolinite can be separated by washing and solid-liquid separation to achieve the purpose of purification. The main process parameter of the acid leaching process is the concentration of acid, which greatly affects the final effect of impurity removal.
Due to its high purity, several minerals have commercial value. These include quartz sand for glass manufacturing and kaolin used as a coating material. However, these minerals contain traces of iron, usually oxides, which can cause discoloration and affect its commercial value. Inorganic acids can be used to remove iron, but these are expensive, not always effective and produce an effluent that requires treatment to remove iron. The purpose of this work is to study the use of organic acids as a cheaper and more environmentally friendly alternative.
The initial work involved the characterization of the sample, which was then leached with chemical and microbial derived organic acids. For the preparation of organic acids produced by microorganisms, the microorganism Aspergillus niger is used, in which molasses is used as a carbon source. The chemically derived acids studied were citric acid, oxalic acid and ascorbic acid.
The best results for quartz and kaolin were achieved using a mixture of citric acid and oxalic acid at a ratio of 2:1 and a temperature of 90 °C, with iron removal rates of 37% and 40%, respectively. This reduces the residual iron content to an acceptable level.
After leaching with an organic acid, the effluent contains ferrous iron, sulfate and residual oxalate/citrate. Synthetic solutions of these components have been tested using an upflow anaerobic sludge blanket (UASB) reactor. The methanogens in the sludge decompose the oxalate into CO 2 and CH 4 , and the heterotrophic sulfate reducing bacteria cause the sulfate to be reduced to sulfide, and the sulfide of iron and other metals precipitates in the presence of HS anion.
