Methods mainly pyrite iron based products are taken: Preparation of high temperature reduction of metal agglomerates (i.e., sponge); recovering iron ore beneficiation; ferrous sulfate or ferric sulfate production; Preparation of Three Ferric chloride; dry and mixed production of iron yellow and iron red products.
First, the recovery of iron
The pyrite ore is used to prepare iron ore concentrate. The method of mineral processing is the most widely used and has achieved remarkable results. Common processes include: magnetization roasting - magnetic separation, reselection, reselection - magnetic separation, re-election - flotation and other joint processes.
The magnetization roasting-magnetic separation process has excellent adaptability to the treatment of pyrite cinder. No matter which type of pyrite cinder is used, this process can be used to select and obtain better sorting index. The magnetization roasting-magnetic separation process can obtain a higher recovery rate; in addition to the above advantages, the magnetization roasting-magnetic separation process has a better de-S effect. If necessary, the calcination conditions can be controlled to reduce the amount of S contained in the slag concentrate to less than 0.3%. Although the magnetization roasting-magnetic separation process has the above advantages, due to the high calcination temperature (700-1000 ° C) and high heat consumption (40 to 450,000 Kcal/t), the calcined slag per ton of calcined slag consumes 40 to 45 kg of heavy oil or 130 ~ 180kg coal powder. Such a large heat consumption makes industrial production unbearable.
Hu Bin Health, Zhang Jingzhi magnetized roasting - magnetic treatment method Tongling sulfuric acid residue, when the magnetization firing temperature controlled at about 700 deg.] C, pulverized coal with a content of 2% to 3%, the firing time 20 ~ 30min, the filling factor of 22.5% kiln When it works best. Finally, 64.13% iron concentrate is obtained, and the recovery rate of iron reaches 84.59%. In addition, with the magnetization roasting-magnetic separation process, Nantong sulfuric acid plant produced 53.90% grade, the yield of 61.58% iron concentrate, the recovery rate of iron in the slag was 89.20%; Shanghai Wujing Chemical Plant obtained grade 58.25%, the yield 75.59%, the recovery rate was 93.16% of the product; Nanjing Chemical Company obtained the grade of 62.90%, the yield was 77.77%, and the recovery rate was 93.47%.
Guizhou Province Metallurgy Design and Research Institute Yang off the phosphorus ore slag carried a single re-election test, to grade 56.08%, a yield of 17.33% recovery of 36.42% iron concentrate. The Zhangzhou Nonferrous Metallurgy Research Institute used the grinding-weakening-medium-magnetic process and the pulsating high-gradient magnetic separator to effectively recover iron from a pyrite cinder and obtain iron concentrate containing TFe49.01%. It is 63.39%.
When the sulfur content in the slag is low, the combined process of grinding-magnetic separation-re-election can produce high-quality iron concentrate. Wu Shizhou carried out research on iron and sulfur removal by this process. After small tests and industrial tests, he obtained an iron concentrate with a grade of 59% and a recovery rate of 70% to 80%. The product contained 0.5% to 0.7% sulfur. Shandong Yantai Chemical Plant adopts a magnetic separation-re-election combined process to obtain iron concentrate products with a grade of 60.0%, a sulfur content of 0.6% and a recovery rate of 73.0%.
The Geological Research Institute of the Ministry of Chemical Industry uses the wet re-election-flotation combined process to treat the slag from a sulfuric acid plant in Shangyu, Jiangxi Province. The iron content in the slag is nearly 60%, and the sulfur content is also 2%. The process is re-elution desulfurization, which is sorted by a coarse sweeping chute. The slag contains only 0.95% sulfur, and then floats by flotation. The content of sulfur in the iron concentrate can be reduced to about 0.6%, the sulfur in the foam product is about 4%, and the total recovery rate of iron in the slag is 85%.
Chen Weiping, Yang Xia, Peng Shiying use demagnetization-alternating magnetic field sorting and ammonia-acetic acid ammonia solution chemical immersion method to treat pyrite cinder containing color metal and iron-poor, and obtain blast furnace with high added value. The iron is mixed with the raw material, the iron grade is 61.4%, and the recovery rate is 58.4%. The tailings after sorting can be used as cement ingredients, and valuable elements such as Pb and Zn can be recovered.
Zheng Xiaohong and Chen Yufeng studied the process of extracting iron from pyrite cinder by sulfuric acid leaching at atmospheric pressure and the influence of main parameters on iron extraction rate. The experimental results show that the factors affecting the iron extraction rate are ranked according to their importance: temperature, time and sulfuric acid mass fraction. When the mass fraction of sulfuric acid is 55%, the temperature is 110 ° C, and the leaching is more than 2 h, the extraction rate of iron is nearly 50%. The method and the process are simple, the cost is low, and there is no secondary pollution.
Peng Rongshan outlined the basic situation of the waste residue produced by the sulfuric acid production of Huangmailing Phosphorus Chemical Group. According to the experimental results of the research institutes and the experience of participating in the work, the process route of the regeneration and utilization of pyrite cinders was proposed.
Second, ferrous sulfate
The pyrite slag is used to prepare ferrous sulfate. The main processes are direct acid leaching of sulfuric acid and high temperature reduction. The high-temperature reduction method has the advantages that the recovery rate of iron in the slag is high, and the disadvantage is that the reaction temperature is high, up to 800 ° C, the reaction process consumes a large amount of energy, and the equipment is expensive; during the direct acid leaching reduction process, the reaction temperature is low and the energy consumption is low. Small, but the recovery of iron in the slag is low. The main reactions of the reduction process are:
Fe+Fe 2 (SO 4 ) 3 =3FeSO 4
Fe+H 2 SO 4 =FeSO 4 +H 2 ↑
Yang Shenghai and Tang Yutang studied the kinetic mechanism of high silicon pyrite cinder in the process of sulfuric acid leaching. The effects of liquid-solid ratio and temperature on Fe leaching rate were investigated. The experimental results show that when the liquid-solid ratio is less than 4.7, the liquid-solid ratio has little effect on the leaching process; when the liquid-solid ratio is ≥ 4.7, the liquid-solid ratio is increased, and the leaching rate is decreased; the reaction grade of sulfuric acid concentration is 1.22; The influence of Fe leaching rate is large, and the temperature increase is beneficial to the leaching of Fe. After leaching for 1h, the leaching rate can well meet the product layer diffusion control shrinkage nucleus model.
1+2(1-x)-3(1-x) 2 / 3 =k·t
Where: x - the mass fraction of iron that has been reacted;
K-reaction rate constant;
T-reaction time, h.
Through chemical analysis and EPMA analysis, it is further proved that the reaction is in good agreement with the product layer diffusion control shrinkage model.
Hou Changjun and Huo Danqun also studied the kinetics of ferrous sulfate reduction process by pyrite slag acid leaching reduction method. Through experiments, under the control of liquid membrane diffusion and mass transfer process, the kinetic model was established:
"1-(1-X B ) 2 / 3 "=kt
Where: X B - reactant conversion;
K-reaction rate constant;
T-time.
The activation energy of the reaction obtained by the experimental data is 1.955kJ/mol, and the relationship between the reaction rate constant and temperature is:
Where: R-gas constant, 8.314 J / (mol · K);
T-temperature, KThe kinetic model was tested by γα with a confidence of >99% and the model accuracy was high. It provides a theoretical basis for the comprehensive utilization of pyrite cinder.
The literature describes the use of pyrite cinder and dilute acid reaction to form iron oxide and ferroferric oxide. Then, the iron slag is subjected to a redox reaction, and the resulting ferrous sulfate solution is evaporated and crystallized to form green cerium crystals. A part of the sludge produced by the production of green carp contains a higher concentration of ferrous sulfate. Therefore, it can be used as a precipitant directly in the sewage treatment process, which can be described as two things. Gao Zhigang, Zheng Jijian, Yu Deyong used pyrite slag and waste sulphuric acid produced from the production of chloromethyl methyl ether as raw materials, and used high-efficiency catalyst and scrap iron scrap as reducing agent to prepare FeSO 4 with high performance.
Gong Zhuqing and Zheng Yajie used pyrite slag to prepare ferrous sulfate by ripening reduction method, and orthogonal experiments showed that the ripening factors affecting the recovery rate of slag iron were: sulfuric acid concentration> ripening time> ripening temperature> sulfuric acid dosage . The reaction temperature of the method is low, and the recovery rate of iron in the slag can reach 90%. The method produces ferrous sulfate with simple equipment, good product quality, and good environmental and economic benefits.
Third, iron sulfate, polymeric ferric sulfate
Li Jinsong and Wang Yanping conducted a gray correlation analysis of five factors affecting the quality of polyferric sulfate. The correlation coefficient (ζ) equation is:
Θ-resolution coefficient
The degree of correlation (γ) equation is:
According to the correlation degree equation, the correlation order of each factor is as follows: sulfuric acid dosage (x 1 )>relative density (x 5 ,kg/L)>concentration of Fe 3 + in solution (x 3 ,g/L)>pH value (x 4)> solution of Fe + 2 concentration (x 2, g / L) .
Jiang Peixia and Wang Shifu used the waste slag of sulfuric acid produced by Jihua Dye Factory and the waste acid of the machinery factory as raw materials, soaked in sulfuric acid with a concentration of 30%, reacted at 70-80 °C for 4 h, and then controlled the polymerization temperature at 40. After reacting at ~60 °C for 2 h, the hydrated iron sulfate is formed, and then basic ferric sulfate is formed, and finally hydrolyzed to form a polymeric ferric sulfate.
Iron sulfate is prepared by using sulfuric acid slag and waste acid as raw materials. Through the study of activated roasting and sulfuric acid concentration, solid-liquid ratio, leaching time and other key process conditions, the best leaching conditions were obtained: the ratio of slag to activator was 4:1, the leaching temperature was 80-90 °C, dip The time was 40 min, the solid-liquid ratio was 0.18, and the waste acid concentration was 55% excess 5%. Under this condition, the iron leaching rate in the slag is over 95%.
Literature introduction After mixing pyrite slag with sulfuric acid, it is heated, water-soluble and filtered to obtain acidic ferric sulfate solution. In the ferric sulfate solution, freshly prepared iron hydroxide was added, and after reacting at 25 to 60 ° C for 2 hours, a small amount of hydrogen peroxide was added to obtain a polymerized ferric sulfate (PFS). The reaction proceeds with the reaction of iron hydroxide and iron sulfate solution. The base of PFS in the solution is increasing. When the amount of ferric sulfate is constant, the basicity of the PFS salt increases as the amount of iron hydroxide increases. The increase in temperature favors the formation of PFS. The addition of hydrogen peroxide to convert Fe 2 + in the solution to Fe 3 + , and the PFS salt basis increases. The coagulation experiment indicated that the PFS prepared by the method had a good turbidity removal effect. The use of pyrite cinder to prepare PFS not only eliminates pollution, but also makes solid waste available. Compared with the method of preparing PFS by using FeSO 2 as raw material and using NaNO 2 catalytic oxidation method, the process has the advantages of quick reaction, no pollution, good economic benefit and the like.
Huangshan discusses the preparation principle, production process and operating conditions of using iron pyrite slag as raw material to prepare inorganic iron-based coagulant such as ferric oxide, ferrous sulfate and polyferric sulfate: sulfuric acid: pyrite cinder = 1.1～1.2 The oxidative polymerization temperature was 60 to 65 ° C, and the oxidative polymerization reaction time was 1 hour.
The literature introduces the use of pyrite cinder to obtain a polymeric ferric sulfate coagulant (industrial product) with excellent coagulation effect. Compared with the preparation method of catalytic oxidation of ferrous sulfate by sodium nitrite, the outstanding advantage is that it eliminates Contamination of sodium nitrite (a carcinogen). The preparation conditions were as follows: leaching with dilute sulfuric acid of V water : V sulfuric acid = 1 for 1 h, stirring appropriately, keeping warm with the heat of the reaction itself, adjusting the pH value of the leachate to about 1.0, and obtaining polyaluminum sulfate coagulation after curing. Agent. The technology is simple in process, easy to obtain raw materials, low in cost, and considerable in economic benefits.
Fourth, iron red, iron yellow, iron black
Wang Yongzhi and Jiang Wei of China University of Mining and Technology studied the process conditions, processes and control parameters in the process of producing iron oxide red from pyrite cinder. The test uses the pyrite cinder produced by Yunnan Honghezhou Phosphate Fertilizer Plant as raw material, and adopts dry and wet production processes to produce iron oxide red products.
Zhang Shun et al. mixed the pyrite slag and carbon powder of the Yellow River Chemical Group sulfuric acid plant in a ratio of 1:1.8 in a nitrogen atmosphere at a temperature of 750 ° C for 30 min, then the reducing slag It is dissolved in 28% sulfuric acid at 87 ° C for 35 min, filtered, rinsed, and dried at 110 ° C. After pulverization, the iron oxide yellow product is obtained. High-quality iron oxide red can be obtained by calcining iron yellow at 310 ° C for 30 min.
The Huataishan pyrite cinder is subjected to sulfuric acid hydrolysis by chemical conversion method, and the high-concentration Fe salt solution is obtained after the clinker is extracted, and the solution is used to produce iron series products such as pigment iron red. The main influencing factors: sulfuric acid concentration, acid slag ratio, chemical formation temperature, and formation time were explored. The test shows that the iron content of the extract of the matured material reaches above 179.8g/L, and the finished content of the iron red is as high as 98.6%, exceeding the national standard GBl863-89.
The two paper mills in Shiyan and Kaishan in Yanbian area are made of paper by sulfite method. The long-term waste of pyrite slag is not only a waste of resources, but also causes great pollution to the local environment. Kang Zhenjin and Zhao Ruozhen succeeded in producing iron oxide red and iron yellow pigments from the slag, which respectively reached the national first-class product quality standards stipulated in GB101-80, H101, H102 (iron red) and GBl862-80 (iron yellow). Significant technical indicators and good economic benefits.
Song Zhouzhou and Wen Puhong proposed a process route for preparing high-grade iron red from iron salt solution prepared from sulfuric acid slag. The sulfuric acid slag of Caijiapo sulphuric acid plant is firstly made into iron salt solution, and the ammonium yellow ferronidium is separated by air oxidation; then the ammonium yellow iron strontium is dissolved in an appropriate amount of water, and the pH value is ≥5 by ammonia water, which produces a red precipitate and is heated to 60. °C, after it is completely precipitated, filtered, dehydrated and dried, pulverized, and finely ground, an iron red product having a Fe 2 O 3 content of 98% or more can be obtained. The recovery rate of iron has also reached more than 80%.
Zhang Ping, Jiang Yuhua, etc. on the slag of Wuhan sulphuric acid plant and the slag of Tongbai sulphuric acid plant, using reverse flotation and selective leaching unless iron oxide impurities, desulfurization by 5% yellow butyl xanthate reverse flotation; In the case of a pH of 8.5, starch is added as a selective flocculant, followed by the de-flotation of octadecyl ether by de-flotation; then leaching with a 5% to 7% ammonium chloride solution at a temperature of 50-60 ° C Calcium and magnesium in the slag; finally oxidized and calcined at 600-700 ° C, and then ground to 320 mesh, to obtain a qualified iron oxide red product, the total recovery rate is above 79%. The quality of the product exceeds the standard of the wet iron oxide red first grade in GBl863-80.
According to reports, Hunan Nonferrous Metals Research Institute and Guangdong Yunfu Pyrite Mine Enterprise Group jointly developed research, using slag-sieving-rinsing-fine grinding-ultrafine condensed reverse flotation-chemical surface treatment-flash drying scheme. Four kinds of iron red products with Fe 2 O 3 content of 99.2%, 98.5%, 95%, and 85%, respectively, can be obtained, and the comprehensive utilization recovery rate of the slag is more than 75%.
Xu Wangsheng and Zhan Shouxiang studied the principle and method of decomposing pyrite slag with sulfuric acid. The preparation conditions and influencing factors of acid hydrolysis reaction and high purity iron oxide were discussed in detail. The decomposition rate of iron oxide in the slag is as high as 95.5%, and the purity of the product iron oxide is 99.56%. The impurity content is lower than the corresponding national standard (HG/T2574-94).
Zhu Yungui and Shi Shanyou studied the synthesis of a-Fe 2 O 3 by hydrothermal synthesis of pyrite cinder by XRD and TEM. The results show that the best acid leaching process of pyrite cinder is to add 7 times of theoretical 75% sulfuric acid. After reacting at 300 °C for 2h, it is leached with hot water and the leaching rate of iron is as high as 93.94%. The metered sinking agent was added at 20 ° C, and the pH of the leachate was adjusted to 2.50 with NH 3 ·H 2 O, and then heated to 65 ° C for 2 h, and 95.1% of iron was precipitated as iron slag. The precipitated iron crucible was made into a suspension of 0.3 mol/LFe(OH) 3 , and the pH was adjusted to 11.30 with 5% NaOH, and then heated at a stirring rate of 600 to 700 r/min and a heating rate of 2.5 ° C/min. Hydrothermal reaction at (172 ± 2) °C for 2 h gave a uniform spherical a-Fe 2 O 3 having a particle size of about 55 mm.
The literature introduces the process of preparing iron oxide yellow by pyrosulfate oxidation method using pyrite cinder as raw material. The effects of Fe 2 + concentration, air flow rate and temperature on seed preparation and two-step oxidation process were studied. The optimum process parameters for the preparation of iron yellow were determined: 1 seed preparation: ferrous concentration 20%～40%, air The flow rate is 01 to 02 m 3 /h, the alkalization is 025, the temperature is 20 to 30 ° C, and the preparation time is 5 to 15 hours. 2 two-step oxidation: ferrous iron concentration 7% to 8%, air flow rate 03 ~ 05m 3 / h, seed crystal ratio of 33%, temperature 80 ~ 85 ° C, oxidation time 50 ~ 70h. X-ray diffraction and transmission electron microscopy showed that the iron yellow was needle-shaped a-FeOOH, and the product reached the HG/T2294-91 standard.
The FeSO 4 extract of the pyrite cinder was leached with sulfuric acid as a raw material, and the iron oxide black pigment was prepared by an oxidation precipitation method, and the performance index of the obtained product reached the first grade standard of HG/T2250-9l.
Five, ferric chloride
Chen Haojie made a corresponding study on the various influencing factors in the process of preparing ferric chloride from pyrite cinder. The specific influencing factors are: the ratio of pyrite cinder to hydrochloric acid, reaction time, nitric acid, and in addition, changing the dosing sequence will also have a certain effect on the precipitation of ferric chloride crystals.
The Pingquan County Sulfuric Acid Plant produces liquid ferric chloride from pyrite cinder. The calcined slag and the 30% to 31% hydrochloric acid are in a ratio of 0.3 to 0.5:1 by mass, and when heated to 40 to 50 ° C, a ferric chloride solution can be formed. 42% to 50% of the liquid ferric chloride is concentrated and cooled to precipitate crystalline ferric chloride, and the purity thereof can generally reach 85% or more.
Sixth, sponge iron
Nanjing Chemical Industry (Group) Co., Ltd. combines the characteristics of sulfuric acid production to make full use of waste heat in the case of low residual sulfur of pyrite slag (ash), using fluid reduction technology to make the iron oxide in the slag Partial reduction to metal sponge iron, after magnetic separation and enrichment, instead of scrap steel directly into steel, produced good economic benefits. The process utilizes the principle of gradual reduction of iron oxides, which converts the higher oxides of iron into lower oxides with solid carbon. The reaction process is as follows:
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