I. Introduction
Guangxi Research herein ore containing a metal sulfide ore, the primary metal minerals in the mine as pyrite, metal may be enriched by flotation recovery of pyrite. Therefore, the recovery of gold-bearing minerals from ore dressing is an important part of the treatment of this type of ore and an important guarantee for improving the total recovery rate of gold.
Entrusted by the mining company, the Institute of Mineral Engineering of the Northwest Institute of Mining and Metallurgy conducted a small-scale ore dressing study on the gold ore. Through repeated exploration of the flotation process conditions and the pharmaceutical system, a rough selection and a sweeping selection were finally adopted. Two selected flotation processes, and obtained the ideal flotation test indicators: the original ore grade is 8.56g/t, the concentrate grade is 50.99g/t, the tailings grade is 0.28g/t, and the gold recovery rate is 97.25%.
Second, the nature of the ore
(1) Multi-element analysis of raw ore
The results of multi-element analysis of raw ore are shown in Table 1.
Table 1 Multi-element analysis results of raw ore
It can be seen from the multi-element analysis of raw ore that the gold deposit contains 8.56 g/t of gold; it mainly exists in the form of gold-containing sulfide; the content of other metal elements is low, and there is basically no recovery value. Gangue minerals mainly silicates and aluminosilicates.
The ore is a typical gold-bearing iron ore type, and pyrite is the main carrier mineral of gold. The gold minerals in the ore are mainly natural gold, silver gold and a small amount of gold and silver. The main metallic minerals pyrite, secondary mineral magnetite, limonite, hematite, and small amounts of trace minerals are sphalerite, yellow copper ore, galena. The gangue minerals are mainly chlorite, followed by quartz , feldspar , calcite , dolomite and mica .
The ore is ferro-mineralized and chlorite is obvious. The pyrite has a fine particle size, and there are also fine-grain inclusions such as magnetite, chalcopyrite, sphalerite, etc., and the relationship with the gangue minerals is complicated, and it is difficult to completely dissociate the monomers. The ore mineral composition is shown in Table 2.
Table 2 Ore mineral composition %
Third, the test results and discussion
The equipment used in the laboratory is Φ240×90 cone ball mill , 1.5L single tank flotation machine and series hanging trough flotation machine. The test water is tap water, the collector is industrial, and the others are chemically pure. The flotation test was carried out according to the determined test procedure.
(1) Grinding fineness test
According to the characteristics of the ore, the test conducted a detailed examination of the grinding fineness. According to the process flow shown in Figure 1, the grinding fineness test is carried out. The influence of grinding fineness on the grade of gold concentrate and the recovery rate of gold is shown in Fig. 2.
Figure 1 Grinding fineness test procedure
Figure 2 Grinding fineness test results
From the grinding fineness test analysis, the fineness of the ore grinding is too coarse and too fine, and its flotation index is not ideal. According to the observation of flotation phenomenon and the change of concentrate grade and recovery rate, some of the gold-bearing minerals did not reach the monomer dissociation when the grinding fineness was coarse, and the gold-bearing minerals and gangues were more connected, especially the poor organisms. , making useful minerals difficult to float, and the recovery rate of gold is low. The grinding fineness is too fine, and the concentrate grade and recovery rate are obviously reduced. This is mainly because the ore chlorite content is high, the chlorite is easy to be muddy, and the grinding time is longer, and the muddy phenomenon is more serious. Therefore, according to the results of the grinding fineness test, it is finally determined that the fineness of grinding is 70%-200 mesh.
(2) Adjusting agent dosage test
In view of the nature and characteristics of the gold mine, we have studied a new flotation regulator T 3 to improve the flotation index and foaming phenomenon of gold rough selection. T 3 was added to the ball mill during the test. The test was carried out according to the procedure shown in Figure 1, and the test results are shown in Figure 3.
Figure 3 T 3 dosage test results
The test results show that with the increase of T3 dosage, the grade of gold concentrate is slightly improved. When the amount of T 3 is 4000g/t, the recovery rate of gold in gold concentrate is 97.08%. Therefore, the test determined that the amount of T 3 was 4000 g/t, and the pH was 8 at this time.
(3) Test for the amount of copper sulfate
The main metal mineral in the mine is pyrite, which is also the main carrier mineral of gold. Pyrite is an iron sulfide mineral that is easy to suppress difficult flotation. In order to maximize the recovery rate of gold, it is necessary to fully activate some of the gold carrier minerals, so that the gold minerals are entrained together to improve the flotation index. The commonly used activators of pyrite are mainly copper sulfate, sodium sulfide, sulfuric acid, oxalic acid, sodium fluorosilicate, sodium carbonate and the like. Copper sulfate was used as an activator for gold-bearing iron ore in this test. The test was carried out according to the process flow shown in Figure 1, and the test results are shown in Figure 4.
Figure 4 results of copper sulfate dosage test
The test results show that Cu 2 + is adsorbed on the surface of pyrite by using copper sulfate as the activator, which forms a copper sulfide film with better hydrophobicity. Its floatability is equivalent to that of the original copper sulfide mineral, and the collector is enhanced in yellow. The adsorption density of the iron ore surface improves the recovery rate of gold in the coarse concentrate to a certain extent. As can be seen from Figure 4, a suitable amount of CuSO 4 is 200 g/t.
(4) Collector test
In order to improve the recovery rate of gold, it is the key to strengthen the flotation of pyrite. It is the primary task to find collectors with better selectivity and strong harvesting power. In the course of several exploratory tests, we finally chose the combination of butyl xanthate and new collector A 3 as the collector of this test to strengthen the collection of gold-bearing iron ore. A 3 is an ester agent with strong catching properties for sulfide minerals and good selectivity. The test was carried out according to the procedure and conditions shown in Fig. 1. The test results are shown in Fig. 5 and Fig. 6.
Figure 5 butyl yellow medicinal test results
Figure 6 A 3 dosage test results
It can be seen from Fig. 5 that with the increase of the amount of butyl yellow, the grade of gold in the coarse concentrate is slightly decreased, and the recovery rate is increasing. When the amount of butyl xanthate is 80g/t, coarse The grade of gold in the mine is 30.11g/t, and the recovery rate is 96.72%. It can be seen from Fig. 6 that with the increase of the amount of A 3 , the grade of gold in the coarse concentrate does not change much, but the recovery rate of gold shows an upward trend. When the amount of the collector A 3 was 125 g/t, the grade of gold in the coarse concentrate was 29.16 g/t, and the recovery was 96.51%. According to the two factors of comprehensive grade and recovery rate, the suitable amount of butyl yellow for gold rough selection is 80g/t, and the amount of A 3 is 125g/t.
(5) Closed circuit test
On the basis of the open circuit test, the closed circuit test is carried out according to the process flow and conditions of Fig. 7, and the test results are shown in Table 3. The closed-circuit test results show that the technical conditions determined by the test are stable and reliable, and easy to produce and apply.
Figure 7 closed circuit test process
Table 3 Closed circuit test results
Fourth, the conclusion
According to the nature and characteristics of the gold ore, a systematic experimental study on the optimization of flotation process parameters was carried out, and the following conclusions were drawn:
1. The metal minerals in the ore are mainly pyrite, and pyrite is the main carrier mineral of gold. The gold minerals in the ore are mainly in the form of natural gold, silver gold ore and a small amount of gold and silver. The gangue minerals are mainly chlorite, followed by quartz, feldspar, calcite, dolomite and mica. Pyrite has a fine particle size and is more complicated in its relationship with gangue minerals.
2, according to the nature of the ore, after a large number of exploration tests, detailed conditions test, the final use of a section of grinding (70% -200 mesh), a rough selection, a sweep, two selected flotation process. The gold concentrate obtained has a grade of 50.99 g/t and a gold recovery of 97.25%. The test obtained satisfactory indicators.
3. The regulator T3 used in the flotation test and the new capture foaming agent A 3 are the newly developed flotation reagents of the Northwest Institute of Mining and Metallurgy, in which A 3 is an ester agent with strong resistance to sulfide minerals. The collection performance is good and the selectivity is good. These two new agents can effectively improve the grade of gold concentrate and the recovery rate of gold.
references:
[1] Li Jianming, Liu Wanfeng, Ma Zilong, et al. Experimental study on flotation optimization of a gold ore [J]. Nonferrous Metals (Mineral Processing), 2004 (3): 16-19.
[2] Chen Liuhong, Zhang He. Experimental study on mineral processing of a gold ore in Guizhou [J]. Nonferrous Metallurgy, 2001, 18 (4): 23-25.
[3] Liu Xiaoyan, Zou Guitian.Experimental Study on Flotation and Gold Extraction Process of Huaqiao Gold Mine in Guizhou[J].Journal of Guiyang College:Natural Science Edition,2006,1(1):14-16.
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