The calcination time test results show that the change of calcination time has little effect on the Au leaching rate. This is because the calcination time is more than 1 h under the selected calcination temperature, and the degree of oxidation of pyrite and arsenopyrite in the concentrate It is quite high, that is, it can open the gold sulfide inclusions, so that the leaching rate of Au is over 90%. Therefore, the roasting time is 1 h. The test results of curing agent dosage show that the curing rate of S and As increases with the increase of the amount of curing agent. When the curing agent dosage is 65% of the theoretical dosage, the curing rates of S and As are more than 65%. It is indicated that the curing rate of S and As can be increased by increasing the amount of curing agent. The comprehensive condition test results show that the solidification rate of solid sulfur and solid arsenic in both tests reached nearly 95%, and the residual rate of gold was nearly 93%. The test results are of great importance. Brake Parts Cleaner Feature:
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Jianjun Wu Ping (Institute of Comprehensive Utilization of Mineral Resources, Chinese Academy of Geological Sciences, Chengdu 610041, China)
Abstract: The use of industrial waste as a curing agent in the difficult selection of metallurgical ore in a certain place, pretreatment of solid sulfur and solid arsenic . Not only the gold in the sulfide is dissociated and leached by cyanide, but also overcomes the disadvantages of S, As in the traditional oxidizing roasting process, and the smoke entering the air to pollute the environment.
Key words: refractory metallurgy ore; pretreatment, CLC number: TF831 Document code: A Article ID:1007-7545(2002)05-0032-03
Pretreating Technology Study on Refractory Gold Ore
KOU Jian-jun, WU Ping
(Chengdu Institute of Multipurpose Utilization of Mineral Resources, CAGS, Sichuan, Chengdu 610041, China)
Abstract:A fixing agent originated from indurstral waste was selected for fixing sulfur and arsenic in pretreating technology of a refractory gold ore.After using the pretreating technology, the gold covered by sulfide minerals could be dissociated from sulfide and then leached by cyanide, and the Malpractice of environmental pollution by smoke contained S and As oxides in traditional oxidizing roasting process of the gold ore could be overcome.
Key words:Refractory gold ore; Pretreating process
The ore composition of a gold mine is complex and contains harmful impurities such as S, As, Sb, and C, and 98.61% of the gold is wrapped by various minerals. The gold concentrate is directly leached and extracted without pretreatment, and the gold leaching effect is extremely poor, and the leaching rate is less than 10%. Commonly used hot-pressure oxidation and microbial oxidation pretreatment methods have strict technical specifications and process conditions, high requirements for equipment fabrication and operation, and are also limited in practical application. The traditional oxidizing roasting process, because S, As is oxidized and then enters the air with flue gas to pollute the environment, especially for mines containing S in about 20%, which does not meet the acid requirements, The difficulty of the process will increase, the production cost will increase, and the input will be greater than the output. Therefore, our choice of solid-sulfur solid-arsenic roasting pretreatment process not only retains the advantages of the common oxidizing roasting method, but also fixes sulfur and arsenic in the calcine, avoiding environmental pollution and reducing the burden of vacuuming. At the same time, industrial waste was selected as a curing agent to make it a wide source of raw materials and low prices.
1 Test raw materials The test raw materials are gold concentrates produced by flotation of a certain sulfide ore. The chemical composition is (%): Au 55.59% g/t, Ag 9.20g/t, S 21.32, Fe 27.48, As 1.62, C 2.02, Sb 0.47, Cu 0.061, Zn 0.033, Pb 0.015, SiO 2 31.91, Al 2 O 3 7.78, CaO 4.18, MgO 1.85. The phase analysis showed that the monomer exposure gold accounted for 1.39%, the sulfide packaged gold accounted for 86.34%, the carbonate packaged gold accounted for 0.94%, and the silicate encapsulated gold accounted for 11.33%. The particle size and grade distribution are shown in Table 1.
Table 1 Particle size and grade distribution of gold concentrate Table 1 Particle size and grade contribution of gold concentrate
Fractional/μm Weight % /% Au grade / (g•t -1 ) Au distribution rate /%
+152 15.32 24.30 6.80
-152~+104 11.52 34.19 7.30
-104~+76 27.76 58.40 28.26
-76~+53 15.14 70.43 18.75
-53 30.26 71.45 38.82
It can be seen that the gold mine contains carbon and antimony in addition to sulfur and arsenic. It is a metallurgical ore containing arsenic and high sulfur, and the main inclusions account for 86.34% of sulfides. Moreover, the gold inlay has a fine grain size, and the amount of gold contained in the -100 μm grain level in the ore accounts for 86% of the total gold amount.
2 Test principle The solid-sulfur solid-arsenic roasting is carried out in the calcine by adding calcium and sodium salts to make arsenic and sulfur form non-volatile arsenate and sulfate during roasting. When the sodium salt is solidified and calcined, the curing agent is costly, and the arsenate formed in the calcine needs secondary treatment (neutralization precipitation). Therefore, the commonly used curing agent is a calcium salt.
The composite curing agent synthesized by industrial waste contains not only the Ca 2+ of S and As in the solid gold concentrate, but also the oxidizing Cl - and Fe 3+ , which are beneficial to the sulfide inclusions. Open. The basic principle of calcium-fixed solid-fixed arsenic is similar. Its main chemical reaction formula is:
4Ca 2+ +2FeS 2 +9.5O 2 =Fe 2 O 3 +4CaSO 4
5Ca 2+ +2FeAsS+9.5O 2 =Fe 2 O 3 +Ca 3 (AsO 4 ) 2 +2CaSO 4
3 Test results and discussion In this test, the pre-treatment method of solid-sulfur solid-solid arsenic roasting was used. Firstly, the condition test and comprehensive condition test were carried out on the main influencing factors such as calcination temperature, calcination time and curing agent addition amount.
3.1 Experimental 3.1.1 pretreatment process different firing temperature test condition with respective sulfur-containing gold concentrate suitable calcination temperature, the temperature is too low, oxidation is slow, so that reach the object of pyrite and arsenopyrite oxidation temperature is too High, easy to melt the concentrate, reduce porosity, form a new inclusion of gold, resulting in a lower cyanide leaching rate of gold. Therefore, the calcination temperature is the most important technical parameter in the calcination process.
The calcination temperature test results are shown in Figure 1. The test conditions are as follows:
Calcination conditions: 120% of the curing agent (accounting for the theoretical amount), roasting constant temperature 2h;
Leaching conditions: L: S = 5: 1, leaching temperature: room temperature, NaCN concentration 0.2%, leaching time 24h, pH = 11~12.
The calcination temperature test results show that the leaching rate of Au increases with the increase of temperature in the selected calcination temperature range, because the oxidation degree of pyrite and arsenopyrite in the concentrate increases with the increase of the calcination temperature. Large, the porosity of the calcined sand increases, and the degree of contact of the cyanide solution with the gold particles increases. Therefore, the calcination temperature was 630 ° C, and the gold leaching rate reached 91.92%.
3.1.2 Calcination time condition test The calcination temperature is selected at 630 °C, and other test fixation conditions are the same as the calcination temperature conditions. The test results are shown in Fig. 2. 
3.1.3 The curing agent dosage test is based on the principle of leaching gold and sulphur-fixing arsenic and minimizing gold depletion. Under the premise of selecting the calcination temperature of 630 ° C, calcination time of 1 h and other fixed conditions and calcination temperature conditions, Calcination curing agent dosage test. The test results are shown in Figure 3.
3.1.4 Control of atmosphere during solidification roasting The porosity of calcined sand is largely determined by the degree of oxidation of pyrite and arsenopyrite during calcination, and the subsequent diffusion rate of sulfur and arsenic. Under the conditions of strong and rapid temperature rise of oxidizing atmosphere, sulfur and arsenic do not have enough time to diffuse to the mineral surface, thus hindering the development of pores. Therefore, controlling the slower calcination rate during calcination will facilitate the formation of a higher porosity calcine. The atmosphere and the chemical composition, phase composition and process of the treated gold concentrate are related to the requirements for arsenic removal and sulfur. The oxidizing atmosphere is too weak, the sulfide oxidation of iron is incomplete, and the inclusions are not fully opened. The oxidizing atmosphere is too strong, and the arsenic trioxide formed by the reaction will continue to be oxidized to form arsenic pentoxide, which in turn reacts with hematite to form iron arsenate. Iron arsenate is a non-porous solid that will hold gold and reduce the rate of gold cyanide leaching in subsequent processes. The atmosphere is generally adjusted in the test by controlling the degree of opening and closing of the oven door. This is not representative and needs to be commissioned and tested during the expansion or production process.
3.1.5 Solidification roasting pretreatment comprehensive condition test According to the solidification roasting pretreatment condition test, we chose to determine the comprehensive conditions: calcination temperature 630 ° C, calcination time 1 h, curing agent addition amount 120% (accounting for the theoretical amount). The comprehensive condition test is shown in Table 2.
4 Conclusion The composite curing agent using industrial waste combination not only has a good effect of solid-sulfur and solid arsenic, but also can turn waste into treasure and reduce environmental pressure. At the same time, the gold sulfide inclusions were opened, so that the gold was understood. The solidification rates of sulfur and arsenic are 94.97% and 94.39%, respectively. This pair of mines located in the hinterland of the national protection zone provides a strong guarantee for the goal of real estate gold.
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Study on pretreatment process of refractory metallurgical ore
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