Many of the world type of copper ore contains molybdenum, molybdenum though with very low (0.01% to 0.1%), but the overall recovery of great value [1]. A porphyry copper-molybdenum deposit in South America is a epithermal copper-molybdenum deposit with copper as its main molybdenum. The ore resource is 1.3 billion tons, the average copper grade is 0.90%, and the associated molybdenum is 0.04%. It has great development prospects. . This paper describes in detail the experimental research on the technical conditions of the flotation process for the copper-molybdenum ore, in order to provide technical basis for the development and utilization of the mine.
First, the nature of the ore
The chemical analysis of the ore and the microscopic identification showed that copper mainly appeared in the form of copper blue and chalcopyrite, and only about 12% of copper appeared in the form of chalcopyrite. Pyrite and molybdenite are rich in ore. The presence of traces of sulphur, arsenic and copper in the sample means that arsenic may enter the copper concentrate. In addition, the presence of some citrate-dissolved copper and a high proportion of cyanide-dissolved copper indicates that the recoverable copper will be less than 100% of the total copper. The sample was ground to 50%-74 μm dissociation analysis. 70% of the copper was dissociated, 20% of the non-metallic mineral pyrite or symbiotic, wrapped in about 10% gangue. The copper mineral has an average particle size of 28 μm. The results of multi-element analysis of raw ore are shown in Table 1. The distribution results of ore copper minerals and pyrite are shown in Table 2.
Second, the test results and analysis
(1) Mixed rough selection test
The flotation of copper-molybdenum ore generally adopts the scheme of copper-molybdenum mixed flotation and mixed concentrate re-separation. In flotation, not only the minerals are required to dissociate sufficiently, but also the appropriate inclusion size is required [1] . In order to investigate the effect of grinding particle size on the flotation effect, a rough grinding grinding fineness test was carried out. The test results are shown in Fig. 1. It can be seen from Fig. 1 that when the ore is ground to -74 μm 40% or finer, the copper rough recovery is higher than 90%. As the grinding fineness increases, the copper recovery rate increases, but after -74μm 50%, the fineness increases again, and the copper recovery rate does not change much. By roughing the test conditions, also influences of other variables, the results showed that the optimum pH range 9.5 to 10.5, when the conventional agents (lime used alkali, dithiophosphate and xanthates as collector , MIBC as a foaming agent, diesel as a molybdenum auxiliary collector), the ore response is very good. Similar results can be achieved by substituting thiocarbamate and SF113 isopropylxanthate as collectors for AP3477 [2] . In the coarse grinding tailing particle size -74μm 50%, lime 2kg / t (added in the mill) to adjust the pH to 10.0, collector AP3477 20g / t (added to the mill) SF113 10g / t, foaming agent MIBC15g /t, coarse flotation time 8min, copper recovery rate of crude concentrate concentrate is 94.40%, copper grade is about 5.0%. Considering that the ore contains a certain proportion of soluble copper, the crude copper recovery rate index is higher than expected.
(2) Mixed selection test
The molybdenite inlay has a very fine grain size, and in order to obtain a qualified molybdenum concentrate, the molybdenum concentrate must be reground [3] . The results of the regrind test are shown in Figure 2. It can be seen from Fig. 2 that the re-grinding has a remarkable effect on the selection of copper minerals, and the optimum regrind fineness is 80%-43 μm. After re-grinding, the copper minerals are selected to float quickly and the selectivity is also very good. The lime is added to make the pH value of 11.0, the grinding fineness is 80%-43μm, the collector AP3477 is 10g/t, and the two sections are refined. A copper concentrate with a grade of more than 35% can be obtained.
(3) Mixed flotation closed circuit test
In order to reduce the loss of the loop, the closed-circuit test effectively increases the recovery of molybdenum in the selective stage by extending the selective flotation time and adding a small amount of collector during the sweeping stage, indicating the presence of molybdenum in the intermediate product. The selection cycle should have sufficient flotation time to ensure good recovery of molybdenum [4] . The flotation closed circuit test process is shown in Figure 3, and the closed circuit flotation test results are shown in Table 3.
(4) Analysis of mixed concentrate
The mixed concentrate contains 35.10% copper, 1.36% molybdenum, 4.60% insoluble content, 125.0 g/t silver content, 0.85 g/t gold content, and the arsenic, antimony and mercury contents of harmful elements are lower than the allowable level.
(5) Copper-molybdenum separation flotation test
In order to effectively recover molybdenum, the concentrate obtained by mixing flotation is subjected to copper-molybdenum separation test, molybdenum-copper concentrate selective molybdenum flotation is pretreated at low pH, and then NaHS is added as an inhibitor of copper and the wind value of the system is controlled. . Nitrogen was used instead of air in the test to minimize the consumption of NaHS and increase its inhibition. The main variables examined were: the number of molybdenum selections, the amount of NaHS, the amount of sulfuric acid, the pH value of the pulp and the Eh value, and the pretreatment time. In the pretreatment stage, sulfuric acid is added to maintain the pH of the slurry at 6.0 to 7.0. It can be seen from the test results of sulfuric acid dosage in Figure 4. The separation effect is best when the pretreatment sulfuric acid dosage is 1.5kg/t, and the pretreatment time is determined to be 20min. The short time is not enough to inhibit the copper mineral floating. In the crude molybdenum selection stage, after the addition of NaHS, the pH of the mixed concentrate was increased to 11.0 and Eh was -535 mV. From the results of the NaHS dosage test in Figure 5, it can be seen that the coarse selection index of molybdenum with 3.0 kg/t NaHS is the best, the molybdenum grade is 8.1%, and the molybdenum recovery rate is 92.0%. Continue to increase the amount of NaHS, resulting in too high pH of the slurry, but the selectivity of molybdenum flotation is reduced. In the rough selection stage of molybdenum, the conditions for inhibiting copper and separating molybdenum from copper are determined. At this stage, the flotation tailings is copper concentrate.
(6) Selective test of molybdenum open circuit
Nitrogen is used instead of air at all stages of molybdenum flotation. Selective flotation of molybdenum was carried out by one rough selection and three selection processes. Since the selectivity of the separation and coarse selection stage was sufficient to suppress copper minerals well, the open-loop selective test gave a molybdenum recovery rate of 83.0% and a molybdenum grade of 47.4%. index of.
(VII) Separation of flotation closed circuit test
The circuit design used in the closed circuit is the full cycle of the intermediate product. The closed circuit test process is shown in Figure 6 (increasing the molybdenum selection). The result is a molybdenum concentrate recovery rate of 93.54% and a molybdenum grade of 46.60%. The copper content in the final molybdenum concentrate is 1.90%. According to the microscopic mineralogical observation, the impurities are mainly insoluble gangue such as silica and clay, which are easily mixed with molybdenum minerals to participate in the flotation process [5] .
Third, the conclusion
(1) The ore type is porphyry copper-molybdenum ore. The copper minerals in the ore are mainly copper blue, chalcopyrite and chalcopyrite, and molybdenum is molybdenite. The ore contains 0.93% copper and 0.042% molybdenum.
(2) The ore is well reflected in the flotation of conventional chemicals. Under the particle size of -74μm 50%, rough grinding and roughing tailing-re-grinding, copper-molybdenum concentrate separation and flotation, molybdenum selection process is suitable for the ore. The nature and final test results confirmed the flotation process. The closed-circuit test obtained a comprehensive index of copper concentrate containing 36.03% copper, copper recovery rate of 89.83%, molybdenum concentrate containing 46.60% molybdenum and molybdenum recovery rate of 75.77%.
(3) The process flow formulated in this test is reasonable in structure and advanced in indicators, and the experimental research results can be used as the technical basis for the development and utilization of the copper-molybdenum ore.
references
[1] Yu Rihui, ten key technologies for mine beneficiation [M]. Beijing: China University of Mining and Technology Press, 2007: 371-372.
[2] Lu Jun, Kong Xiaowei. Experimental study on preferential separation and separation of a molybdenum-copper sulfide ore [J]. Comprehensive Utilization of Minerals, 2006, (4): 21-23.
[3] Hu Zhen, Li Hanwen, Zhang Hui. Research on rational beneficiation process of a copper-molybdenum ore [J]. Mining and Metallurgy Engineering, 2008, (6): 29-32.
[4] Yu Juan, Yang Hongying, Zhou Changzhi, et al. Experimental study on separation flotation of a refractory copper-molybdenum mixed ore [J]. Non-ferrous metals: mineral processing, 2008, (6): 6-8.
[5] Ma Jing, Zhang Wenzhao, Li Shuben. Molybdenum ore beneficiation (2nd edition) [M]. Beijing: Metallurgical Industry Press, 2008.
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