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(1) Analysis of the metal tailings to be treated, for quartz and feldspar as gangue minerals, SiO2 content is greater than
35wt% metal tailings, using quartz separator and jib equipment to separate the quartz and part of the feldspar
The content of SiO2 is less than 35wt%; for metal tailings to be treated with SiO2 content less than 35wt%, it is not necessary to separate
Quartz and feldspar;
(2) Determination of the total iron content in the metal tailings obtained in the step (1), according to the amount of total iron, the metal tailings
For high-iron tailings and low-iron tailings, high-iron content metal tailings are treated by total carbon reduction for harmless treatment; low
Iron content metal tailings are treated by a modified melt oxidation method;
The full carbon reduction method is:
(a) Recycling iron
Containing carbon (C) is greater than 80wt% of non-coal under reducing conditions so that conversion of Fe2O3 Fe3O4, FeO into
Iron, which absorbs CO2 with CaO, and magnetically recovers iron after cooling. The chemical reaction formula is:
6Fe2O3+C = 4Fe3O4+CO2
2FeO+C = 2Fe+CO2
CaO+CO2 = CaCO3
The amount of anthracite and CaO added is calculated according to the chemical reaction formula, and the amount of anthracite and CaO added is ensured to ensure complete reaction.
10% more than the theoretical value, the anthracite, CaO and metal tailings are respectively ground to -200 mesh, uniformly mixed and then calcined back.
Roasting in a rotary kiln, the calcination temperature is 1100 ° C ~ 1150 ° C, the calcination time is 25-30 min; the mixture after calcination
After cooling, the iron is recovered by magnetic separation;
(b) Recovery of heavy metals from the exhaust
Heavy metal mercury , lead , cadmium and arsenic are in the form of Hg, Pb, Cd, As in the form of Hg, Pb, Cd, As, or sublimate into the exhaust gas.
According to the order of gravity: Hg > Pb > Cd > As is recovered by acid or sodium hydroxide solution, and the chromium is in the form of Cr2O3 with magnetic
Sex, recovered when magnetically selected iron;
The improved melt oxidation process is:
Adding the dolomite-reducing dolomite, grinding the dolomite, separating quartz and part of the feldspar metal tailings to -200
The mixture is uniformly mixed and sent to an oxidizing roasting rotary kiln for calcination at a calcination temperature of 1200 ° C to 1250 ° C, and roasting time.
20-25min, forming a molten metal tailings mixture, using a high pressure water gun to quickly quench the molten material; dolomite
The addition amount is calculated by the following formula. The acidic oxides in the formula include SiO2, Fe2O3, Al2O3 and SO2, and the basic oxide includes
CaO, MgO, K2O, Na2O; heavy metals such as mercury, lead, chromium and arsenic enter the exhaust gas in the form of oxides, and are recovered by acid or sodium hydroxide solution.
Chromium is in the form of Cr2O3 and is magnetically recovered.
Whether using the full carbon reduction method or the improved melting oxidation method, the organic beneficiation additives are decomposed under high temperature roasting.
The intermediate and trace elements are converted into hydrazine-soluble active compounds, and the residual heavy metals are converted into silicate-stabilized compounds.
2. The method for treating harmless metal tailings according to claim 1, wherein 3 wt% to 5 wt% is used.
The pH of the metal tailings after the harmless treatment of the sulfuric acid solution is adjusted to 7.0 to 7.5, dried and ground to be used as a fertilizer raw material and matrix.
Or use on non-acid soils.
3. The method for treating harmless metal tailings according to claim 1, wherein the total iron (Fe) content is
Based on 8.0wt%, the metal tailings with a total iron content greater than 8.0wt% are high-iron content metal tailings, and the total iron content is less than
8.0 wt% of metal tailings is a low iron content metal tailings.
4. The method for treating harmless metal tailings according to claim 1, wherein the metal tailings are iron
Tailings, bauxite tailings, molybdenum tailings, the lead tailings zinc, nickel tailings, tailings copper, manganese tailings, tailings tungsten, tin or gold tailings tailings.
Method for treating harmless metal tailings
Technical field
[0001] The invention belongs to the technical field of cross-cutting of ecological environment and mining cycle economy.
Background technique
[0002] 1. Status and harm of metal tailings in China
[0003] According to incomplete statistics, before 2000, the total amount of tailings in China was 5.026 billion tons, of which iron tailings amounted to 2.614 billion.
Tons, the main non-ferrous metal tailings amounted to 2.109 billion tons, the gold tailings amounted to 272 million tons, and the other 0.31 tons. Emissions in 2000
The amount of tailings reached 600 million tons. Based on this calculation, the total amount of existing tailings should be more than 8 billion tons, and still generate 500 million per year.
The growth rate of tons of tailings (the Ministry of Industry and Information Technology issued on June 19, 2009: the comprehensive utilization potential of tailings is abundant).
[0004] In addition to occupying a large amount of land, these tailings also destroy the ecological environment, causing serious soil erosion, dust and pollution.
Water source. Geological disasters such as mudslides, landslides and dam breaks that are lurking in a large number of tailings reservoirs endanger our society and economy.
sustainable development.
[0005] For example, the black storm that occurred in the northwestern region in 1993 was due to a dust storm in a city in Jinchang, Gansu.
340,000 tons of nickel tailings were thrown into the sky and formed a rare black storm, killing 85 people and missing 31 people, 264 people
Injured; 120,000 heads (only) livestock died, lost, 730,000 heads (only) livestock injured; 370,000 hectares of crops were affected, 4330
The housing collapsed and the direct economic loss reached 725 million yuan. Another example is September 8, 2007 in Linyi City, Shanxi Province.
A dam-breaking incident occurred in the Tieshan Iron Tail Mine in the county, causing 268 people to be killed or missing.
[0006] 2. Current status and problems of metal tailings resource utilization in China
[0007] (1) Utilization status
[0008] 1) Secondary sorting of tailings to recover valuable metal elements and non-metal elements
[0009] Most metal mines in China are symbiotic and associated deposits. National Development and Reform Commission in December 2006
The guidance for the comprehensive utilization of the “11th Five-Year†resources issued on the 24th pointed out: “Continue to support Panzhihua, Baiyun Obo, Jinchuan
Construction of three major resource comprehensive utilization bases... Focusing on iron ore, copper ore, bauxite, gold, lead and zinc, and tungsten ore
Several tailings re-selection demonstration projects. "Domestic mining enterprises in various countries have carried out recycling of valuable metal elements to varying degrees.
jobs.
[0010] 2) Metal tailings for agricultural use
[0011] In 1971, Zhang Fudao and Jiang Xiaoli cooperated with the former Shandong Zibo Aluminum Factory to use the red mud of the plant and elute the sodium salt with water.
47 field fertilizer tests were carried out in Jinhua, Zhejiang Province and Jiangxi Red Soil, and the crops were rice, rape, barley, corn, and large.
Beans, broad beans, and citrus increased by 8.5% to 17.0%. The results were published in the Shandong Institute of Soil and Fertilizer in 1972.
In the annual report (in 1970, the Institute of Soil and Fertilizer, Chinese Academy of Agricultural Sciences was decentralized to Dezhou, Shandong Province, and Shandong Province in Shandong Province).
The Soil and Fertilizer Institute, at the time of the "Cultural Revolution" period, all academic journals were suspended, and the "annual report" form and brothers used by soil and fertilizer
Unit exchange). In 1973, Zhang Fudao and others used Zhaoyuan high- phosphorus gold tailings to produce superphosphate, which was hosted by the Shandong Provincial Department of Chemical Industry.
An annual production of 5,000 tons of phosphate fertilizer plant was completed. The study concluded that “the addition of sulfuric acid to remove cyanide from the gold residue and the production of calcium.
"Study" published in the 1974 Scientific Research Annual Report of the Shandong Institute of Soil and Fertilizer and the Shandong Provincial Department of Chemical Industry, 1974, No. 5
In the newspaper, because the environmental awareness was too shallow, only consider the removal of cyanide, did not consider the problem of heavy metal pollution, and did not measure
Heavy metal content in tailings.
[0012] 3) used as building materials
[0013] Metal tailings are used for producing ordinary wall bricks, cement raw materials, raw materials for decorative materials, paving materials, glass ceramics
Raw materials, etc.
[0014] 4) Used as a filling material for mine goaf.
[0015] 5) Used as a soil conditioner and a magnetized fertilizer by magnetization.
[0016] 6) Planting crops by reclamation of tailings.
[0017] (Guo Jianwen, Wang Jianhua, etc., China's iron tailings resources status and comprehensive utilization, Modern Mining, 2009 (10): 23 ~
25)
[0018] (2) There is a problem:
[0019] 1) low utilization of tailings
[0020] According to statistics, by 2008, China’s mine land reclamation rate was only 10% to 12% (including coal mines), metal
The comprehensive utilization rate of tailings is only about 8.2%.
[0021] 2) diffusion of heavy metal contaminants
[0022] According to Huang Lanqi et al., Dabaoshan tailings is directly used to manufacture magnetized fertilizers, and the heavy metal content is seriously exceeded.
problem. Among them, Cr exceeds 6.8 times and Pb exceeds 12.7 times. Fertilizer application to the soil will cause the spread of heavy metal pollutants (Yellow)
Lancome et al., Research on Comprehensive Utilization of Dabaoshan Metal Sulfide Mine Tailings, Metal Mine, 2009(7): 164~168.); Ma Steel
Pb, Cd and Cr in the magnetized tailings soil improver were seriously exceeded. The term "magnetization" is very important in mineral processing, but in agriculture,
In particular, soil fertility is of little significance. When China’s fertilizer (including soil conditioners) production licenses are registered, only nutrient inclusions are included.
Quantity, heavy metal content and field test results, regardless of magnetization, so-called magnetized fertilizer and magnetized soil improver and magnetized water
The same is the advertising language.
[0023] 3) Problems with tailings reclamation
[0024] 1 tailings reclamation planting crops will be enriched with heavy metals, which are unsafe for both humans and livestock.
[0025] 2 there is still a hidden danger of debris flow. Tailings, also known as tailings, have physical properties like flowing sand, even on the tailings pond.
Soil planting trees are also not safe. More than 90% of the tailings dams in China are built in the valley, which is tens or even hundreds of meters above the downstream residential area.
A metal processing tailings harmless, characterized in that the method comprises the steps of:
December 24, 2019