Hard to choose tailings also have spring! Brief Analysis of Comprehensive Utilization Technology of Domestic Tailings
The report shows that the accumulated stock of tailings in China is huge, and comprehensive utilization is promising. In the past five years, China's tailings annual emissions have reached more than 1.5 billion tons. While the accumulation of waste rock and tailings pile inventories of nearly 600 tons, of which 43.8 billion tons of waste rock dumps, waste rock and 75% iron-copper mining coal gangue generated; tailings stockpiling 14,600,000,000 tons, 83% of tailings iron ore, copper, gold mining formation, utilization great potential.
National Construction Pilot Base
In recent years, with the improvement of mineral processing technology and the increasing tension of mineral resources, the country has realized that the development and utilization of mining waste is a new target for mine development, and the comprehensive utilization and treatment of tailings is the key project. one.
In 2011, the Ministry of Industry and Information Technology organized the first batch of pilot projects for the construction of industrial solid waste comprehensive utilization bases, and identified 12 pilot areas including Hebei Chengde.
On August 10 this year, the Ministry of Industry and Information Technology announced the first batch of pilot bases approved by the Ministry of Industry and Information Technology for self-assessment, provincial-level industry and information technology department audits, expert review and on-site inspection.
According to reports, Chengde City and Chenzhou City have the most outstanding achievements in the comprehensive utilization scale and comprehensive utilization efficiency of industrial solid waste.
In 2015, the comprehensive utilization of tailings in Chengde City reached 50 million tons, and the comprehensive utilization rate reached 31%, which is much higher than the national comprehensive utilization level of tailings. The utilization of fly ash in Shuozhou City is 42.24 million tons, the comprehensive utilization rate is 80%, and the comprehensive utilization value reaches 18 billion yuan, accounting for 18% of the city's total industrial output value.
In the country's high priority, this batch of pilot bases has made major breakthroughs and progress in technology:
1 Promoted a number of advanced and applicable comprehensive utilization technologies. New building materials technology such as tailings high-concentration concentrated dry storage technology, comprehensive extraction and selection technology of ferro- phosphorus - titanium have been promoted and applied, and technologies such as fly ash to manufacture lightweight refractory bricks have been industrialized.
2 Break through a number of key common comprehensive utilization technologies. The research and development of gold, molybdenum , fluorite , silica sand, single magnetite tailings to prepare microcrystalline decorative sheet, microcrystalline foam ceramics and microcrystalline wear-resistant materials technology. Ash extract alumina, silica technology, fly ash producing a ceramic fiber technology, fly ash producing a nitrogen oxide present in the refractory art home and abroad in a leading position.
Below, Xiaobian introduces several domestic tailings processing technologies and excellent projects.
Tailing paste thick and stockpiled
Paste/high concentration tailings ground storage was first proposed by Professor Ronbinsky of the University of Toronto and should be applied to the Kiddcresk mine in Ontario, Canada. Despite the constraints of pulp concentration and high-concentration slurry transportation technology at the time, development was sluggish. However, in recent years, due to the tailings storage problem of Australian laterite aluminum mines, this technology has developed rapidly and 19 projects have been built in Australia (2008 data show).
At present, China's tailings pond paste storage is still in its infancy. In the true sense, only Baotou Baiyun Oboxi madness mining company has been operating. Its iron ore tailings with an annual output of 7 million tons are thickened by paste thickeners. deal with.
Zijin Group Zijinshan Gold and Copper installed four paste thickeners for the treatment of copper wet process plant's neutralization slag, gold selection plant cyanide slag.
Paste tailings are tailings slurries that are concentrated in a paste state after the flocculant is added to the tailings. In this type of slurry, the solid material in the slurry has a particle size of ≤20μm greater than 20%, which can prevent water from oozing out, thereby maintaining the moisture of the paste, preventing the larger particles from segregating, and playing during the pumping process of the paste. Lubrication.
To put it simply, the paste tailings have a high viscosity and do not seep. In the case of heavy rain, the water will flow down the slope. At the same time, when the tailings are exposed to the sun, although the surface will appear to be dry, this is only the evaporation of water, the particle size distribution is unchanged, and there will be no dust in the atmosphere.
The concentration of tailings in the formation of the paste varies depending on the type of tailings, which is related to the size distribution of the tailings, the clay content, the particle morphology, the statics, the mineral properties, and the amount of flocculant. According to the investigation, bauxite, red mud paste percent solids of 45%, Copper, Lead zinc tailings was 75%, 72% gold tailings, therefore, as the case may be paste emission concentration by trial and error The result depends on.
Tailings pre-enrichment - suspension roasting - magnetic separation efficient recovery
Iron ore new suspension roasting technology - tailings pre-enrichment - suspension roasting - magnetic separation efficient recovery, this technology is a complex and difficult choice for Northeastern University for the characteristics of complex refractory iron ore with low grade and many iron minerals. A new process for iron ore "pre-enrichment-suspension roasting-magnetic separation (PSRM)".
The technology forms a precise regulation of multi-phase transformation of iron minerals, suspension state maintenance of heterogeneous ore particles, high-efficiency low-temperature reduction in regenerative heat, and iron phase control in cooling process through a large number of researches on the theory, process and equipment of suspension roasting technology. A series of new technologies such as latent heat recovery.Since 2014, Northeastern University has carried out PSRM laboratories and pilot tests of complex refractory iron ore resources such as the eastern tailings of Anshan Iron and Steel Group, the Yanshanshan Rock Mine, the Donganshan Iron Ore, and the Jiugang Powder Mine. Good roasting effect and sorting index.
At present, the technology has been gradually promoted in major domestic steel enterprises. Among them, Angang Mining Group has completed the preliminary design of 28.5 million t/a PSRM in the eastern tailings, and it is estimated that it can recover 2.6-300 million tons of qualified iron concentrate. On June 25, 2016, Jiugang Group launched a 6.6 million t/a wine steel ore powder PSRM renovation project, which is expected to increase the annual profit and tax by more than 100 million yuan. The Hejiaying Iron Mine of Hegang Group plans to complete the feasibility study of the project by the end of 2016, complete the project design in May 2017, carry out the construction in June 2017, and conduct the test in July 2018.
Preparation process of tailings glass ceramics
The use of tailings to make glass-ceramics has been extensively studied at home and abroad. At present, the methods for producing tailings glass-ceramic decorative sheets mainly include calendering, casting and sintering.
The calendering method, the technology created by the former Soviet Union in the 1970s, the domestic technology is not yet mature, the crystallization in production is difficult to control, the plate bursting seriously, and the yield is low.
The casting method is to cast the molten and clarified glass liquid on the mold, and then to be crystallized and annealed in the crystallization furnace, which has high requirements on the quality of the mold, low production efficiency and low yield.
The sintering method is the first in Japan. It is the water quenching of molten glass to obtain the pellets and crystallization into secondary firing. At present, the scale and benefits have been formed in China, and more than 99% of the entire building decoration glass-ceramic market uses sintering. Production process.
In 2005, the Department of Materials and Chemical Engineering of the Southern Institute of Metallurgy developed a new process for the production of microcrystals - the particle rolling method. It is a method for preparing a tailings glass-ceramic plate on the basis of fully absorbing the advantages of the melt casting method and the sintering method, and is a process for producing a crystallized glass by controlling the particle gradation of the water-quenched glass and the amount of the particles added. method. The specific method is as follows:
The tailings were sieved through 20 mesh and 80 mesh square sieves for use. Various raw materials were weighed according to the chemical composition of the base glass. The uniformly mixed glass batch is filled with enamel and melted in a silicon molybdenum rod electric furnace at a melting temperature of 1400e for 2 hours. After the molten glass liquid is quenched into granules and dried, weigh a certain amount, and then the molten glass liquid is taken out from the furnace, and the weighed glass granules are poured into the glass liquid and stirred uniformly. Finally, the mixture of the glass liquid and the water-quenched glass particles was poured on an iron plate and calendered into a glass sample, wherein the amount of the water-quenched glass was 9.43%, and the amount of the glass melt was 90.57%. The glass samples prepared by the particle rolling method were nucleated and crystallized under different heat treatment systems, and finally the glass ceramic samples were obtained.
Polyacrylamide (PAM) is a water-soluble polymer, which is insoluble in most organic solvents, has good flocculating properties, can reduce frictional resistance between liquids, Can be divided into non-ionic, anionic, cationic and amphoteric four types.
When PAM is used for flocculation, it is related to the surface properties of the species being flocculated, especially the potential, viscosity, turbidity, and pH of the suspension. The kinetic potential of the particle surface is the reason for particle inhibition. Can reduce the potential and condense.
Granular polyacrylamide flocculant cannot be directly added to sewage. It must be dissolved in water before use, and its aqueous solution are used to treat sewage.The water in which the particulate polymer is dissolved should be clean. Generally tap water is suitable for formulating polymer solutions. Strong ACID, strong alkali, high salt water is not suitable for preparation. Water at room temperature is ok, no necessary to heat. Dissolution is slow when the water temperature is below 5 ° C. Increasing the water temperature will accelerate the dissolution rate, but above 40 ° C will accelerate the degradation of the polymer and affect the use effect. The solution concentration is recommended to be 0.1% -0.3%.
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