Experimental study on gold dressing of a high arsenic and high sulfur refractory gold ore
With dwindling disposable gold mineral resources, gold smelter gradually refractory gold concentrate as part of the production of raw materials [1]. Refractory gold include gold-containing arsenic sulfide, a carbonaceous deposit, the ultra-fine disseminated gold and gold polymetallic sulfide ore, wherein the arsenic sulfide gold reserves the highest [1]. Such ores are often wrapped in a gold micro-fine (microscopic gold or secondary) in a lattice form or disseminated pyrite and arsenopyrite, and thus difficult to be dissociated by mechanical means such fine grinding (or Exposed), which leads to difficulty in recovery of cyanide leaching. It usually needs to be enriched by beneficiation and further processed [2] .
The beneficiation of high arsenic and high sulfur gold ore usually has two methods of re-election and flotation. In general, be recycled to the natural free coarse gold and gold-bearing quartz ore veins, natural or gold containing small amounts of sulfide inclusions contained in arsenopyrite, reselection method should be adopted; natural wrapped in gold sulfide ores in It should be recycled by flotation [3] . This experiment starts with process mineralogy and analyzes the occurrence state of gold, arsenic and sulfur in a high-arsenic and high-sulfur refractory gold ore in Anhui. Through the difference of the properties of different gold-bearing minerals, the re-election is determined. The process and the conditional test determine the optimum process parameters.
First, the test materials
Other metallic minerals Some High Arsenic Sulfur GOLD Anhui mainly pyrite (partially broken, gum altered to pyrite), pyrrhotite, arsenopyrite, etc., see a small amount of local Nugget sphalerite , galena, brass metal sulfide ore; gangue minerals seldom, carbonate minerals mainly calcite and dolomite, followed by clay minerals, chlorite minerals and sericite alteration, and a small amount of quartz, feldspar Wait. Some gold exists in the form of fine-grained natural gold, and most of them are closely symbiotic with arsenic pyrite, rubber pyrite and gangue, which is extremely difficult to dissociate. In general, the mine contains arsenic, high sulfur, and gold is difficult to dissociate, which is a typical refractory gold deposit. The chemical analysis results of the main elements of the ore are shown in Table 1. The distribution and balance calculation of gold are shown in Table 2. The distribution and balance calculation of sulfur are shown in Table 3.
As can be seen from Tables 1 to 3, the arsenic grade of ore is 2.83%, and the sulfur grade is 38.51%. Except for gold and iron, other valuable metal elements are extremely low, and it belongs to high arsenic and high sulfur gold ore. Gold has a higher distribution in natural gold, pyrite and arsenopyrite, but the gold grade in pyrite is lower at 1.45 g/t. The arsenic in the ore is mainly distributed in the arsenopyrite, and the sulfur is mainly distributed in the pyrite.
Second, mineral processing test research
(1) Test plan argumentation
Since this sample contains 18.01% of ferromagnetic mineral pyrrhotite, this mineral contains the lowest gold and arsenic. Therefore, it is easy to obtain qualified sulfur concentrate by magnetic separation method. Gold and arsenic are in magnetic separation tailings. Enriched; the natural floatability of arsenopyrite and pyrite is similar, and the pyrite minerals are large in quantity and low in gold content. Therefore, the flotation method can neither separate the arsenic and sulfur, nor can the gold be further rich. Set; however, the density of natural gold and arsenopyrite is larger than that of pyrite, which can be separated by re-election method to recover gold and arsenic.
(2) Magnetic separation fineness test
The particle size composition of the ore sample is an important factor affecting the magnetic separation results. The test firstly tests the grinding fineness under the condition of magnetic field strength of 79.61 ka/m. The test procedure is shown in Figure 1, and the test results are shown in Table 4.
It can be seen from Table 4 that as the fineness of grinding increases, the grades of gold, arsenic and sulfur in the sulfur concentrate change little, but the recovery rate of sulfur decreases slightly with the increase of grinding fineness. When the ore fineness is -200 mesh 50%, the sulfur recovery rate is 17.97%, which is the optimal index. Considering that the first value metal of the mine is gold, followed by sulfur, the fineness of grinding is determined by the final re-election index.
(3) Magnetic field strength test
The test flow chart is shown in Figure 2, and the test results are shown in Table 5. It can be seen from Table 5 that with the increase of the magnetic field strength, the grades of gold, arsenic and sulfur in the magnetic sulfur concentrate are not changed much, and the recovery rate of gold and arsenic is also small. Only the recovery rate of sulfur is slightly increased, but After the magnetic field strength exceeds 79.61 KA/m, the increase rate begins to decrease. Considering the comprehensive consideration, the magnetic field strength is selected to be 79.61 KA/m.
(4) Re-election fineness test
The ultimate goal of the test is to obtain gold concentrates with better indicators, and re-election is the main operation for enrichment of gold, so it is necessary to determine the optimal inclusion fineness by re-election. The magnetic separation tailings of Fig. 1 were used as the fineness condition test for continuing the shaker re-election of the ore. The test results are shown in Table 6.
It can be seen from Table 6 that with the increase of grinding fineness, the grade of gold in the re-selected concentrate is significantly increased from 8.75% to 16.96%, but the recovery rate drops significantly from 53.92% to 32.54%. This result indicates that on the one hand, grinding is beneficial to the monomer dissociation of gold minerals, thereby improving the concentrate grade; on the other hand, gold minerals or gold-bearing mineral particles are too fine, and shaker re-election is difficult to recycle. Considering that this concentrate needs to be selected, from the perspective of achieving a higher gold recovery rate, it is determined that -200 mesh accounts for 50% as the optimal inclusion particle size for shaker rough selection, and this fineness and the appropriate particle size obtained during magnetic separation. Match.
(5) Re-election of concentrates, re-grinding and re-selection of fineness test
The whole process of the selection test is shown in Figure 3, and the test results are shown in Table 7;
As is known from Table 7, the ore is first subjected to magnetic separation and shaker rough selection at a fineness of -200 mesh of 50%, and re-selection of the coarse concentrate to further finely grind to -200 mesh 75% to obtain a gold grade of 16.84 g/ t, the recovery rate is 47.63% of re-elected gold concentrate, and at the same time, 45.49% of arsenic is enriched to gold concentrate. The re-selected tailings still contain 38.88% sulfur, and the recovery rate is as high as 71.73%, but the arsenic content is 2.19%, which cannot be used directly. Therefore, it must be reprocessed to reduce the arsenic content to the industry. Application requirements.
Third, the conclusion
(1) The metal minerals in a high-arsenic and high-sulfur gold mine in Anhui are mainly pyrite (partially fragmented, eroded into pyrite), pyrrhotite, arsenopyrite, etc., and the gold part is fine-grained naturally. The form of gold exists, most of which are closely related to arsenic pyrite, rubber pyrite and gangue, and are difficult to dissociate. They are typical refractory gold deposits.
(2) The ore is firstly subjected to magnetic separation to obtain a qualified sulfur concentrate containing 36.11% sulfur, 0.03% arsenic and 17.81% sulfur recovery rate. The magnetic separation tailings are then subjected to a shaker re-election-grinding-re-election process. A gold concentrate containing 16.84 g/t of gold, 13.63% of arsenic and a gold recovery of 47.63% can be obtained.
references
. [1] Xue light, Experimental Study in Nagae Sec roasting gold concentrate containing arsenic from acid leaching residue in the leaching of gold and silver cyanide [J] Gold, 2008 (1): 4041î€
[2] Li Dingxin, Wang Yonglu. Precious Metallurgy [M]. Changsha: Central South University of Technology Press, 1991î€
[3] Luo Xinmin, Wei Dangsheng, Ye Congxin.Study on the Process of Flotation and Arsenic Reduction in Mashan Gold Mine of Anhui Province[J].Hunan Nonferrous Metals,2007(10):6
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