A gold mine in Henan is a layer-controlled deposits, the geological structure of the mine complex, folds, faults, strong magmatic activity frequently, by contact metamorphism and hydrothermal metasomatic alteration and mineralization generally strong. The prospective reserves are considerable. Disseminated micro fine ore, mainly fissure gold, gold inclusions intergranular gold distributed in the form of pyrite, arsenopyrite and other metal minerals. Pyrite and arsenopyrite are the main carrier minerals of gold. The ore types are mainly pyrite type and quartz dolomite pyrite altered rock type. According to the relative content of minerals in the ore, the metal minerals in the ore are mainly sulfides, and pyrite is dominant, followed by arsenopyrite. Through the multi-selection test of the beneficiation process, the crude grinding-mixing flotation-re-grinding-gold-sulfur separation process is adopted, and the obtained test index is the gold concentrate yield 12.42%, the gold grade 55.2g/t, and the gold recovery rate 80.56%. sulfur 51.52%, containing 1.68% arsenic.
First, the nature of the ore
(1) Ore type and mineral composition
The natural type of ore is pyrite type and quartz, dolomite pyrite altered rock type. The structure of the ore is mainly secondary metasomatic structure, crystalline granular structure, and scale-like granular crystal structure. The structure of the ore has a pleated structure, a massive structure, a strip-like structure, and a disseminated structure. The main mineral composition and content of the ore are shown in Table 1.
Table 1 Relative content of main mineral components in ore (%)
(2) Ore chemical composition
The results of chemical analysis of ore are shown in Table 2, and the results of iron phase analysis are shown in Table 3.
Table 2 Results of multiple analysis of ore chemistry (%)
Table 3 Results of phase analysis of iron in ore (%)
(3) Main mineral characteristics in ore
The size of natural gold and silver gold ore is generally between 0.1 and 0.005 mm. It is closely related to metal sulfides. It is mainly distributed in the form of fissure gold, inclusion gold and intergranular gold in pyrite and arsenopyrite. Or in gangue minerals.
Pyrite is the most abundant metal mineral in the ore and one of the main metal sulfides in the ore, accounting for about 36% of the total minerals. Pyrite mainly produces self-formed and semi-automorphic grains, and some of them are produced in the form of crystal grains. Cubic self-formed pyrite is common. The particle size is uneven, the maximum particle size is 2 to 5 mm, and the fine-grained pyrite is 5 to 10 μm. The general particle size distribution is between 0.07 and 2 mm. It is about 86% larger than 0.074mm, and only 14% below 0.074mm. Due to the influence of tectonic action, pyrite fractures are relatively developed, and natural gold and silver gold deposits are often embedded in the fissures of pyrite. Pyrite is closely embedded with gold minerals and is one of the main carrier minerals of gold.
Aromatic sand is the main arsenic-containing mineral in ore, which is self-formed, semi-automorphic or grain-like. Columnar, rhomboid self-formed crystals are common. The size of the arsenopyrite is uneven, the coarse particles can reach 1 to 3 mm, the fine particles are 10 to 20 μm, and the general particle size is 0.1 to 2 mm. Pyrite and arsenopyrite, native gold, silver gold, galena and quartz, carbonate gangue minerals closely associated, often euhedral crystal shape or semi-wrapped shape coarser pyrite Among them, some are intercalated with pyrite in the gangue or independently produced in the gangue. The poisonous sand is also one of the main gold-bearing minerals in the ore. The gangue minerals are mainly quartz, often filled in the fissures of pyrite, or the pyrites constitute the "texture" structure. See a small amount of fine-grained gold minerals wrapped in quartz. The particle size of quartz is generally 0.03 to 1 mm. Quartz, sericite, muscovite and carbonate minerals pyrite, arsenopyrite and other metal intimately associated minerals, disseminated form, banded ore.
Second, mineral processing test research
(1) Selection of process flow
The main carrier minerals of gold in ore are pyrite and arsenopyrite, and gold is closely related to pyrite and arsenopyrite. The embedding characteristics of gold indicate that the size of gold inlay is fine, with fissure gold, inclusion gold and intergranular gold. Mainly. According to the nature of the ore and our years of research experience on gold mines, three schemes have been developed: first, priority re-election; second, lime-sulphur-floating gold-floating test; third, first mixed flotation, re-grinding, gold-sulfur separation test the study. However, although the first scheme has a certain enrichment of concentrates, the recovery rate is low, and there are a large number of medium mines. The tailings contain 2 to 3 g/t of gold, which cannot be discarded. The second scheme has lower flotation indexes. The recovery of sulfur needs further activation. The amount of lime is large, gold is also strongly suppressed, and the technical and economic indicators are not satisfactory. The test results show that the third scheme is feasible and the technical and economic indicators are reasonable, so the scheme is carried out. Detailed test.
(2) Mixed flotation test
The purpose of the mixed flotation test is to initially enrich the gold and to abandon a large amount of tailings under a rough grinding condition.
Mixed flotation was carried out for the type and dosage test of the adjusting agent, the fineness test of the grinding and the test of the amount of the collector . On the basis of this, the optimum process conditions for the mixed flotation were determined. The recommended process and conditions are shown in Figure 1. See Table 4.
Table 4 Mixed flotation closed circuit test results (%)
Figure 1 Hybrid flotation recommended process
(III) Separation test of gold and sulfur in mixed flotation concentrate
Although the gold-sulfur mixed flotation test gold concentrate has a high recovery rate, the gold grade is low. From the identification of the ore, it is known that the primary inlaid grain size of gold in the ore is mainly fine-grained gold. Therefore, the gold can be further dissociated by re-grinding, and the sulfur mineral flotation is inhibited to enrich the gold concentrate, which can improve the gold concentrate. grade. The process and conditions of the mixed concentrate gold and sulfur separation test are shown in Figure 2.
Figure 2 Process and conditions of concentrate gold and sulfur separation test
The sample used in the test was a coarse concentrate prepared by a mixed flotation closed circuit test. The lime sulfur suppression dosage test, the collector condition test and the grinding fineness test were respectively carried out.
1. Gold and sulfur separation inhibitor test
It has been experimentally determined that effective and inexpensive lime is used as an inhibitor. Fixation conditions: grinding fineness - 320 mesh 86%, the same amount of one-stage flotation, two-stage sweeping agent, butyl xanthate 10g / t, No. 2 oil 10g / t. The test results are shown in Figure 3.
Figure 3 Gold sulfur separation inhibitor test results
Tests have shown that the use of lime can effectively inhibit sulfur, the overall gold grade and gold recovery rate, the appropriate amount of lime (for raw ore) is 1kg / t.
2. The fineness test test of mixed coarse ore concentrate gold and sulfur separation grinding (results shown in Figure 4) shows that the gold can be further dissociated by re-grinding, which is beneficial to the flotation to improve the grade of gold concentrate and reduce the sulfur. Gold content. The comprehensive gold grade and gold recovery rate, the appropriate grinding fineness of the test is -320 mesh accounted for 86%.
Fig. 4 Results of fineness test of mixed coarse ore concentrate
3. Type and amount test of mixed crude concentrate gold and sulfur separation collector
Test fixed conditions: CaO dosage (for raw ore) 1kg/t, grinding fineness - 320 mesh 86%. Other conditions and results are shown in Table 5.
Table 5 Test results of types and dosages of mixed crude concentrate gold and sulfur separation collector
Tests have shown that although the selectivity of the mixed agent is better, the collection ability is weaker and the recovery rate of gold is lower. However, the price of butyl ammonium black medicine is also relatively expensive, so a single collector, diced yellow syrup, can be used, and only a small amount can be used to effectively achieve gold and sulfur sorting.
4. Comprehensive condition test of mixed flotation gold and sulfur separation
The final integrated process and conditions of the test are shown in Figure 5. Finally, a gold concentrate with a yield of 12.42% and a grade of 55.20 g/t was obtained, and the gold recovery was 80.56%. It contains 51.52% sulfur and 1.68% arsenic.
Figure 5 Mixed flotation - the final process and conditions of gold and sulfur separation
Third, the conclusion
1. The process of mixing flotation-mixing re-grinding-gold-sulfur separation is a suitable treatment method for treating such high-sulfur arsenic-containing gold-containing refractory ore.
2, using a rough selection, two sweeps, a selected closed-circuit mixing flotation test, can obtain a yield of 43.20 from the ore containing Au 8.45g / t, containing S up to 20.5%, containing As 1.94% %, containing 18.82g / t of Au, containing 3.94% As, the gold recovery rate of 95.59% of the mixed concentrate; after re-grinding, gold and sulfur separation process, the yield can be obtained as a yield of 12.42%, gold grade 55.2g / t The gold concentrate with a recovery rate of 80.56%, which contains 51.52% sulfur and 1.68% arsenic.
3. The gold concentrate obtained from the high-sulfur arsenic-containing refractory gold ore test is subjected to metallurgical immersion gold test, and the gold leaching rate is greater than 95%. Therefore, the process has a certain guiding effect on the rational development and utilization of the mine.
4. After the multi-selection test, the rough grinding-mixing flotation-re-grinding-gold-sulfur separation process has achieved the ideal index, and the process has the characteristics of simple process, easy operation and strong adaptability. The process is reasonable and feasible.
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