Study On Collaboration Treatment Of Low Content Pyrite And Red Mud From Large Amount Of Industrial Solid Waste

The large of industrial solid waste red mud discharged from the alumina production process has the characteristics of strong alkalinity and complex alkali components.Pyrite is often associated with non-ferrous metal sulfide mines and coal mines,It is difficult to use due to its low grade and difficulty in comprehensive utilization,A large number of mines are discarded in the process of mining and selection,and they are weathered and oxidized in the natural environment to release a large amount of hazardous substances such as sulfuric acid.The accumulation of red mud and low-content pyrite not only takes up land,but also causes groundwater and soil pollution.Aiming at the characteristics of alkali-containing red mud and acid production from pyrite,this study proposes the idea of synergistic neutralization treatment of alkaline red mud and acid liquid produced by pyrite.That is to analyze the release law of free alkali and chemically bound alkali during the red mud leaching process,and optimize the acid production environmental conditions of low-content pyrite,realize the stabilization treatment and disposal of red mud desalination and low-content pyrite deacidification,and lay the foundation for the soil utilization of both.The alkali material in the red mud is mainly bound alkali,in which the content of free alkali is about 3.59×10^-3 mmol/g,and the content of bound alkali is about 0.261mmol/g.In the process of ultra-pure water leaching,the dissolution of free alkali is the main factor.The respectively dissolution amounts of Na⁺and K⁺are 5.1×10^-3mmol/g and 0.34×10^-3 mmol/g,the dissolution of chemically bound alkali is slow.In the process of hydrochloric acid leaching,the free alkali and the bound alkali dissolve simultaneously.Within the first 10 hours,a large amount of Na⁺dissolves quickly,with a dissolution amount of about 0.69 mmol/g,Na⁺,K⁺and Mg²⁺are first dissolved from the red mud,affected by the ionic radius and ionic charge,Ca²⁺begins to dissolve after 10h.During the sulfuric acid leaching process,in the first 10 hours,Na⁺dissolves quickly,with a dissolution amount of about 0.79 mmol/g;in addition to the influence of ionic radius and ionic charge,SO₄^2-combines with Ca²⁺to form slightly soluble Ca SO₄,leading to the dissolution time of Ca²⁺Delayed,so Ca²⁺began to dissolve after 18h,and the dissolution time was later than the hydrochloric acid leaching process.Thiobacillus ferrooxidans was selected and enriched by acid mine wastewater,with a species abundance of about 50%,which can significantly increase the acid production and reduced sulfur conversion rate of low-grade pyrite.The optimal conditions for the oxidation of low-grade pyrite by Thiobacillus ferrooxidans to produce acid are:the initial p H is 2.00,the ore dosage is 10 g/L(the ore is passed through a 100 mesh sieve),and the bacterial concentration is 15%(bacteria The number of liquid is 1.68×10⁸ CFU/m L),the output of H⁺is about 0.9 mmol/g,and the conversion rate of low-valent reduced sulfur is about 53.7%.During the oxidation process,ORP is maintained at about 500 m V,which can maintain good microbial activity.Experiments on the alkali neutralization and Co-treatment of red mud by pyrite biological oxidation acid leachate show that the acidic biological leachate has a better neutralization and dealkalization effect on red mud.The SO₄^2-in the acid leachate combines with the Ca²⁺in the red mud to form micro Dissolved calcium sulfate and Fe³⁺participate in the dealkalization in the form of H⁺generated by hydrolysis during the treatment process,causing SO₄^2-and Fe³⁺to migrate into the red mud.The removal rate of Na⁺is about 97.3%.When the reduced sulfur content of low-content pyrite is 1.41%,the mass ratio of low-content pyrite to red mud is 7:100,the red mud deacidification of bulk industrial solid waste and the deacidification of low-grade pyrite can be realized,and the red mud after the removal of alkali by biochemical leaching The mud has no back alkali effect and the nature is stable.