Kaolin because of its excellent performance and a wide range of applications, has been continuously developed and utilized, but due to the lack of understanding of the comprehensive utilization of mineral resources, the utilization of resources is often ignored, followed by a large number of kaolin tailings piled up, resulting in a waste of resources, but also destroyed the ecological environment of the mining area. In recent years, with the depletion of kaolin mineral resources and the strengthening of environmental awareness, domestic universities, research institutions and enterprises have begun to study the resource utilization of kaolin tailings, and the utilization of kaolin tailings has been continuously improved.
Instead of aggregate such as sand and gravel for building materials
Feng Baoxia of Yanzhou Mining Group found that the washed kaolin tailings can be used to prepare concrete hollow bricks instead of construction sand. Yang Huaming and others of Beihai Branch of Yanzhou Mining Group applied for a patent on "Kaolin Tailings Composite Powder and Its Application in Ready-mixed Concrete. The patent records kaolin tailings, calcium oxide, water glass and other substances through mechanical grinding to obtain kaolin tailings composite powder, the powder completely can be used in concrete, the mechanical properties of concrete, durability is not affected at all.
Preparation of lightweight wallboard using kaolin tailings slag
Ye Huoyao uses kaolin tailings slag to prepare lightweight wallboard, and applies for an invention patent "a method for preparing lightweight wallboard using kaolin tailings slag".
Production of cement-based materials
Yang Yan made low-grade metakaolin by grinding and calcining kaolin from a kaolin tailings in Fogang, Guangdong. The activity changes of low-grade metakaolin, low-grade metakaolin and slag, low-grade metakaolin and silica fume compound under different excitation methods were studied. On this basis, low-grade metakaolin was used in fiber reinforced cement products.
Extraction of Sodium Silicate from Kaolin Tailings
Sodium silicate, commonly known as bubble flower alkali, its aqueous solution commonly known as water glass, is a mineral binder. A method for extracting sodium silicate from kaolin tailings by low temperature and medium pressure method is provided. The specific steps include: kaolin tailings are crushed, ball milled, sieved and classified; The raw materials are wetted with ethanol, stirred and mixed evenly with excess sodium hydroxide, distilled water of a certain proportion is added, stirred and poured into the inner container of a reaction kettle, alkali leaching test is carried out, and the solid-liquid solution is washed to neutral filtration, and dried to obtain sodium silicate. This invention improves the comprehensive utilization value of kaolin tailings, the process is simple and the energy consumption is low.
Preparation of low iron quartz sand for photovoltaic glass
Shang Dexing et al. conducted process mineralogy research on a kaolin tailings in Fujian. After full-size grinding-classification-gravity separation-magnetic separation-scrubbing-flotation, the content of 0.6~0.1mm grain fraction is more than 95%,SiO2Content of 99.29%,Al2O3Content of 0.27%,Fe2O3The content of quartz fine sand is 0.0029%, which meets the quality requirements of low-iron quartz sand for solar photovoltaic and photothermal glass.
Preparation of pure white carbon black
Ren Xin et al. used Suzhou kaolin tailings as raw material to prepare white carbon black through high temperature calcination, acid leaching, filtration and drying. The obtained silica was characterized by XRD, Fourier transform infrared spectrometer and BET, with a purity of more than 98.32 and a specific surface area of 350m.2/g。
Extraction of Rubidium Chloride from Kaolin Tailings
A method for extracting rubidium chloride from kaolin tailings is disclosed by Yuan Tiechui et al. of Central South University. First of all, the kaolin tailings are crushed by disk grinding and sieving to obtain kaolin fine ore powder, the kaolin fine ore powder is evenly mixed with the leaching agent, and the evenly mixed powder is poured into the pre-heated acid solution for acid leaching to obtain the acid leaching solution. The obtained leachate was adjusted to have a pH close to neutral, followed by calcium removal to obtain a leachate containing rubidium. Using 4-tert-butyl-2-(α-methylbenzyl) phenol solution diluted with sulfonated kerosene for extraction, using hydrochloric acid solution for stripping and other processes to obtain crude rubidium salt products, which were dissolved and recrystallized to obtain high purity rubidium salt products.
Preparation of glass products
Guilin Institute of Electronic Technology Chen Guohua and others use kaolin tailings as the main raw material, and then add the appropriate amount of magnesium oxide, boric acid, ammonium dihydrogen phosphate and other substances by roasting method to prepare low-temperature sintering performance of microcrystalline glass, which has the characteristics of dielectric constant and low expansion coefficient and high resistivity, to meet the requirements of microelectronic packaging.
Preparation of ceramic-related articles
Wang Hai of Guilin Institute of Technology used kaolin tailings and dolomite to prepare expansion coefficients of 6.5~7.1 ×10-6/℃(30-380) glass ceramics, which have the characteristics of high hardness and acid and alkali resistance. Using kaolin tailings as the main raw material, Lu Xiaobo developed a high-temperature ceramic glaze through scientific experiments.
Preparation of inorganic polymer flocculant
Polymeric aluminum ferric chloride (PAFC) is a new type of polymer flocculant, which is based on aluminum chloride and introduced ferric ion, and formed by hydroxyl bridging and copolymerization in the process of solution hydrolysis. In the treatment of drinking water, industrial water, domestic water, domestic sewage and industrial sewage purification effect is obvious.
Using α-Al2O3Good activity in the acid, the use of kaolin tailings not only successfully prepared the basic polyaluminum ferric chloride in line with national standards, but also the residue of silica enrichment treatment, used in the preparation of water glass and architectural coatings filler.
Preparation of Kaolin Tailings Lightweight Through Hole Ceramsite
Jiang Wenlan has opened a kind of kaolin tailings light through-hole ceramsite. The main points of its technical scheme are: kaolin tailings light through-hole ceramsite consists of kaolin tailings, high-viscosity attapulgite clay, powdered kaolin foaming agent, activated clay waste residue, hollow microsphere, expanded perlite, expanded vermiculite, light calcium carbonate and ferrous sulfate. The ingredients are mixed, extruded and granulated, dried, roasted, insulated and screened, and then sealed and packaged as kaolin tailings light through-hole ceramsite. Kaolin tailings light through-hole ceramsite has the characteristics of large specific surface area, small bulk density, high water absorption, superior air permeability, beautiful appearance without odor, good light strength, micropores and macropores. When used to cultivate or plant all kinds of seedlings, flowers and vegetables, the roots of plants will absorb the nutrients of water or liquid fertilizer from the light through hole ceramsite of kaolin tailings, so as to ensure the good growth and high survival rate of plants. It is suitable for preparing soilless culture matrix and nutrient soil.
Other kaolin tailings comprehensive utilization
The combined beneficiation process of magnetic separation, gravity separation and flotation is adopted to obtain high-quality quartz sand, tourmaline, mica and other concentrate products, and at the same time, the residual kaolin products are also recovered. The magnetically selected iron silicate minerals can be used as building materials or cement raw materials, which maximizes the comprehensive recovery and utilization rate of kaolin tailings secondary resources, realizes zero discharge of tailings, and achieves high economic and social benefits.
In view of the characteristics of Yunnan Lincang kaolin with high aluminum, potassium, sodium, iron, titanium and other harmful metals, low content and complex mineral composition, a new type of kaolin comprehensive utilization and no tailings project was designed.
Kaolin tailings contain mineral components such as quartz, muscovite, feldspar and residual kaolin. Kaolin concentrate, mica concentrate, feldspar concentrate, quartz concentrate, etc. can be obtained by means of gravity separation, desliming, screening, flotation, machine and other sorting methods and appropriate process flow, and even mineral processing without tailings can be achieved. Using SiO contained in kaolin tailings2、Al2O3, K2O its Na2O, CaO, MgO and other useful components of the characteristics, and then add other necessary components, and then through melting, water quenching, molding, heat treatment, demoulding, polishing and other deep processing to prepare ceramic glass products. With the increasing environmental pressure and the implementation of energy saving and emission reduction, the full use of kaolin tailings is imminent.