I. Introduction
Polymetallic sulfide ore containing gold and silver used in the test, a higher content of valuable components, minerals for metal recovery are gold, silver, copper, lead, zinc, sulfur. However, the nature of the ore is complex and the symbiotic relationship between the various minerals is very close. Gold and silver minerals are mostly encapsulated in sulfide ore, and the size of the inlay is fine. Forming a chalcopyrite different periods, flash zinc sulfide minerals, galena and pyrite dip account each other, therefore, between the minerals and between the silver and the gold-bearing minerals sulfide mineral larger separation difficult.
Through the ore dressing test of the ore, it is believed that the single flotation, mixed flotation-mixed concentrate cyanidation-flotation multi-metal separation, ore cyanidation-flotation process can achieve comprehensive recovery of metal minerals. Among them, the gold and silver leaching rate and the total recovery rate of the ore cyanidation-flotation process are the highest, and the flotation indicators are similar in each process.
Second, the nature of the ore
(1) Material composition and embedding characteristics of ore
The chemical multiple analysis of ore and the phase analysis of copper, lead and zinc minerals are shown in Tables 1 and 2. The analysis indicates that the ore is a polymetallic sulfide ore containing gold and silver, and gold, silver, copper, lead, zinc and sulfur all have comprehensive recovery value.
Table 1 Chemical multiple analysis of ore
Table 2 Analysis of copper, lead and zinc phases
The ore minerals in the ore are pyrite, pyrite, chalcopyrite, sphalerite, galena, chalcopyrite, beryllium copper, natural gold, fluorite ore, silver bismuth ore, deep red silver ore. , tellurium, lead, copper, blue, malachite, gangue minerals are quartz, chalcedony, calcite, sericite, kaolinite, barite.
The symbiotic relationship seen by various minerals is more complicated. The copper, lead and zinc minerals formed in different periods are filled with irregular, fine veins or veins. The symbiotic relationship between copper, lead and zinc minerals formed during the same period is more closely related. Some chalcopyrite and galena are present in sphalerite in the form of fine-grained unmixed crystals, and a small amount of chalcopyrite is cloud-like (ie ultramicroscopic emulsion). (form) distributed in sphalerite. Therefore, it is difficult to separate copper, lead and zinc minerals by mechanical means. The degree of oxidation of lead is high and the flotation recovery rate will be affected.
(2) The occurrence state of gold minerals
The gold minerals in the ore are natural gold, produced in silver gold and gold and silver mines. It is mostly round, irregular and fine veins. The gold inlay has a finer particle size, with fine gold (≤0.01mm) accounting for 47.95%, fine gold (0.01-0.037mm) accounting for 49.16%, and medium gold (≥0.037mm) accounting for 2.89%. Natural gold is present in the gangue minerals such as sulfide and quartz in the form of inclusion gold, interstitial gold and fissure gold, of which the inclusion gold is 67.23%, the crystal gap gold is 22.89%, and the fracture gold is 9.88%. There are more gold-bearing minerals and minerals associated with gold, see Table 3. The main gold-bearing minerals are sphalerite, followed by galena, sericite and quartz.
Table 3 Distribution of natural gold in each gold-bearing mineral
(3) The state of occurrence of silver minerals
There are many silver minerals in the ore, mainly silver mine, silver beryllium, deep red silver, natural silver and so on. Natural silver is low in content. Silver minerals are closely related to sulphide, chalcopyrite and other sulfides, and are mostly encapsulated by or in the form of droplets and irregular granules. The particle size of the silver mineral is generally between 0.01 and 0.03 mm.
Third, the beneficiation test process and test results
The process of mineral processing of gold-silver-containing polymetallic sulphide ore is generally complicated. For the nature of the ore used in this test, three sorting processes have been established through experimental research, namely single flotation process, mixed flotation - mixed concentrate cyanide - Flotation multi-metal separation process and ore cyanidation - flotation process. The principle flow chart is shown in Figure 1, Figure 2 and Figure 3, respectively.
Figure 1 Single flotation process
Figure 2 Mixed flotation-mixed concentrate cyanidation-flotation multimetal separation process
Figure 3 Single ore flotation process of ore cyanidation-flotation process
The test results obtained by using the three beneficiation processes to treat the ore are shown in Table 4, Table 5 and Table 6, respectively. The liquefaction component of cyanide leaching has not been chemically analyzed, and the leaching rate and recovery rate of gold and silver are calculated from the content of gold and silver in the leaching residue. The leaching rates of gold and silver in the mixed concentrate were: 41.44% for Au and 18.22% for Ag. The leaching rates of gold or silver cyanide in ore are: 90.50% for Au and 29.73% for Ag. Although some metal ions are dissolved in the metal cyanide during the cyanidation process, the amount of dissolution is very small, which is neglected in the test.
Table 4 Single flotation test results
Table 5 Mixed flotation-mixed concentrate cyanidation-flotation multi-metal separation test results
Table 6 Raw ore cyanidation - flotation test results
Fourth, discussion
(1) Mixed flotation
The metal minerals in the ore are closely related to each other, and the metal minerals are often symbiotic with the gangue minerals in the form of veins, plaques, clumps or breccia. The metal mineral and the gangue mineral can be dissociated under rough grinding conditions. Although fine grinding is beneficial to improve the mixed concentrate index, fine grinding will make the concentrate decontamination difficult, which is not conducive to the cyanidation of the mixed concentrate and the separation of various metal minerals. Therefore, the fineness of the grinding flotation is determined as -200 mesh content can be 60%. The collector is made of ethyl ketone and butylamine black. The pH of the pulp is controlled between 11 and 12. The recovery of gold, silver, copper, zinc and sulfur can reach over 90%. The lead in the ore has a lower grade and a higher degree of oxidation, so the lead recovery rate of lead is lower.
(2) Copper and lead flotation
For polymetallic sulphide ores containing copper, lead and zinc, because the floatability of copper and lead is better than that of zinc and sulphur, the process of preferential flotation of copper and lead to suppress zinc sulphur is generally used [1] . For mixed concentrates containing a variety of metal minerals, in addition to the need to re-grind to improve the dissociation of metal minerals, it should also be treated with a drug to improve the sorting effect. The combination of activated carbon and Na 2 S has the best effect. The use of Na 2 S after cyanidation of mixed concentrate or ore can also eliminate the activation of sphalerite and pyrite by copper ions dissolved during cyanidation, but the amount of Na 2 S should not exceed 400g/t, otherwise it will Copper and lead recovery rates have declined.
The mixed concentrate flotation copper lead collector is Z-200, and the inhibitors are ZnSO 4 and Na 2 S 2 O 3 . For the flotation flotation after the cyanidation of raw ore, the copper-lead collector is treated with ethyl ketone, the inhibitors are ZnSO 4 and Na 2 SO 3 , and the use of water glass as an inhibitor of gangue minerals is better.
(3) Separation of copper and lead
The floatability of chalcopyrite and galena is similar. The separation of copper and lead in mixed concentrate is usually difficult. In addition, the excess flotation agent in mixed concentrate is also an important factor in the difficulty of copper and lead separation. After comparison of various chemicals and separation methods, it is considered that the method of using lead-inhibiting copper is suitable, and the method is beneficial to ensure the copper concentrate grade and recovery rate. Before the separation of copper and lead, an appropriate amount of activated carbon is used to remove the copper-lead mixed concentrate, which is beneficial to improve the selectivity of copper-lead separation. Lead inhibitors work best with K 2 Cr 2 O 7 . The copper concentrates have good selection indexes in the three processes. Lead is low in grade in the ore, high in oxidation, and muddy in high grinding fineness, so it is difficult to float to form fine Mineral products.
(4) Zinc-sulfur flotation and separation
After flotation of copper and lead by mixed concentrate, activation of sphalerite with CuSO 4 and inhibition of pyrite by CaO can achieve separation of zinc and sulfur, and obtain zinc concentrate and sulfur concentrate with better indexes. After the flotation of copper or lead in the ore cyanide leachate, zinc-sulfur flotation is required. However, since the pyrite is strongly inhibited by the residual lime and cyanide in the slurry after cyanidation, it is difficult to float the pyrite. Therefore, zinc-sulfur flotation is dominated by flotation of sphalerite. The obtained zinc-sulfur mixed concentrate is further separated by zinc and sulfur to improve the zinc concentrate grade, and the sulfur concentrate grade and recovery rate are low.
(5) Pretreatment cyanidation leaching gold and silver
The content of metal sulfides in the ore is relatively high, and these minerals increase the consumption of cyanide and oxygen, which affects the cyanide leaching process of gold and silver [2] . Alkali pretreatment and low concentration cyanide leaching can effectively inhibit the adverse effects of sulfides (mainly iron sulfide minerals in ores) on cyanidation leaching, reduce the consumption of cyanide and oxygen, and facilitate the reaction of gold and silver cyanidation. . Alkali pretreatment is to intensify aeration of the slurry under alkaline conditions (pH=11~12) before cyanide leaching to oxidize the ferrous iron and sulfur in the ore to ferric iron and sulfate.
The ferric iron and the base further act to form iron hydroxide precipitate and adhere to the surface of the sulfide ore, preventing and reducing the formation of the ferricyanide complex and the thiocyanate ion in the cyanidation reaction, and the action of the sulfide ore and oxygen, thereby reducing cyanide and oxygen. Consumption, increase the cyanide leaching rate of gold and silver. Alkali pretreatment has obvious effects on mixed concentrate and ore cyanidation. The alkali leaching ore, the gold leaching rate of mixed concentrate leaching increased from 25.16% to 41.44%, and the gold leaching rate of raw ore leaching increased from 61.78% to 90.50%. The dissolution rate of silver minerals in cyanide is lower than that of gold [3] , and silver minerals are mostly present in sulfides and fine-grain inclusions. Therefore, the silver leaching rate is low.
Disintegration of mixed concentrates is difficult. Despite various measures such as regrinding, washing and adding desorbent, the cyanide leaching rate of gold and silver is still unsatisfactory. Although increasing the regrind fineness can slightly increase the leaching rate, too fine ore is not conducive to the flotation separation of metal minerals. In order to avoid the complexity of the process, the grinding fineness is controlled at -360 mesh content of 90%, and the alkali pretreatment is carried out after concentrated washing twice. The gold and silver leaching rates of the mixed concentrate are 41.44% and 18.22%, respectively.
V. Conclusion
For complex ore containing gold-silver polymetallic sulfide ore, the single flotation process is relatively simple, and the flotation separation of copper, lead, zinc and sulfur is better, but without the output of gold and silver products, gold and silver can only be enriched. In the concentrate, and the total recovery rate of gold and silver is relatively low. Although the mixed concentrate cyanide can obtain gold and silver products and improve the recovery rate of gold and silver, the mixed concentrate is difficult to remove the drug, the gold and silver leaching rate is low, and the process is complicated and difficult to control, which easily causes the fluctuation of the gold and silver leaching rate. The leaching rate of gold or silver in the ore is high, and the sorting effect of cyanide tailings metal sulfide ore is similar to that of single flotation and cyanidation of mixed concentrate. Only sulfur (iron sulfide mineral) is affected by residual lime and cyanide in the slurry. The inhibition of the compound is low.
Through the comparison of three kinds of smelting schemes, the gold-silver-containing polymetallic ore is treated by alkali pretreatment cyanidation extraction of gold and silver and cyanide tailings polymetallic flotation separation process, and the gold and silver cyanide leaching rate and total recovery rate are high. And achieved the purpose of comprehensive recovery of polymetallic.
references:
[1] Qiu Jicun. Mineral Processing [M]. Beijing: Metallurgical Industry Press, 1987, 365.
[2] Xu Tianyun, Xu Zhengchun. Gold cyanidation and smelting [M]. Shenyang: Shenyang Golden College, 1985, 30~36.
[3] Manual for Comprehensive Utilization of Mineral Resources [M]. Beijing: Science Press, 2000, 407.
Author unit
Liaoning Institute of Geology and Mineral Resources (Hu Zhigang)
Shenyang Nonferrous Metal Research Institute (Dai Shujuan)
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