Experimental study on recovery of sericite from gold mine flotation tailings

Mineral resources as a non-renewable resource, with its decreasing, the use of tailings to recover useful minerals as an industry, has gradually attracted people's attention. Studying the comprehensive utilization and processing technology of mineral resources is of great significance for the rational and rational development and utilization of mineral resources.

Metro Laizhou City, Shandong Province gold ore daily processing raw ore 1500t, recovery of gold by flotation method, the amount of flotation tailings beneficiation plant Nissan is 1350 ~ 1390t, accounting for the total amount of ore. At present, floating 90% to 93% of the tailings storage capacity is nearly 300 million, and it is growing at a daily rate of 1000t. Such a large amount of tailings not only takes up a lot of land, pollutes the surrounding environment, but also wastes a lot of valuable resources. The current output of Xincheng Gold Mine tailings X-ray diffraction analysis showed that the content of the tailings sericite about 25%, or sericite Xincheng Gold Mine abandoned 375t per day. If it can be recycled, the economic benefits will be considerable. Recovering valuable components from mine tailings is the development direction of mining enterprises and a strategy for sustainable development of enterprises.

Based on the analysis of the tailings properties, the study systematically studied the process conditions for recovering valuable components of sericite from tailings and determined the process of recovering sericite.

First, tailings properties

The results of multi-element analysis of tailings are shown in Table 1. It can be seen from Table 1 that the valuable element recoverable in the tailings is Au, but the gold grade is lower. The oxide content of Si, Al, K, indicates that the tailings contain a certain amount of sericite.

The results of ray diffraction analysis of tailings show that the content of sericite in tailings is about 25%, other non-metallic minerals are quartz , square solution 25% stone, feldspar, etc. In the sericite sorting, impurities such as quartz should be removed. .

The results of tailings particle size analysis are shown in Table 2. As can be seen from the results in Table 2, the tailings sample size is fine. -0.074mm content is

54.50%, especially -0.043mm, has a higher grain size, which makes it difficult for the sorting operation. From the distribution of 43.46% of sericite in various grades of tailings, sericite is mainly distributed in fine-grained grade (-0.0308mm) and coarse-grained grade (+0.10mm), and its occupancy rate is 44.26%. , 36.05%, but the grade of sericite in each grade is close, only +0.28mm, -0.0308mm grade sericite grade is higher.

Second, research on the recovery process of sericite

(1) Formulation of the process plan

The sericite in the tailings is fine in size, and has little difference in relative density with gangue minerals, and is non-magnetic. It is difficult to separate and enrich it by physical separation methods such as re-election and magnetic separation. Flotation is the most effective method for separating and enriching sericite. Because sericite is poorly floatable, it is close to other gangue minerals, so it is necessary to use a selective agent.

The key to the recovery of sericite from flotation is to increase the difference in floatability between quartz and tailings. Sericite can be floated either in acidic or alkaline media. According to the flotation agent dissociation equilibrium theory, a fatty acid collector is preferred under alkaline conditions, and a cationic amine collector is commonly used under acidic conditions. It is generally believed that flotation of mica in an acid circuit is more efficient and more selective. Therefore, in this study, the sericite was sorted and recovered in an acidic medium by flotation.

(2) Comparison test of collectors

According to the flow shown in the figure, the experiment was carried out to optimize the flotation conditions. Under the conditions of fineness of grinding, a comparison test of -0.074mm 85% different collectors was carried out to select the best combination of collectors for flotation. The test results are shown in the table. Comparison of the results of Table sorting effect can be that the use of coal and oil composition stearylamine collector more appropriate. Under the condition of the dosage, the tailings can be obtained by a rough selection of 360g/tK ₂ O content, and the recovery rate is 6.3% and 57.59%. From the theory of hydrophobic flotation flotation, it can be seen that the size of the sericite inlay is small and the surface is less hydrophobic, which is the main reason for the low recovery rate of sericite. In the rough selection of sericite, the sericite surface is activated by a combination of octadecylamine and kerosene, and at the same time, in the case of high-speed agitation, mechanical energy is input, the energy barrier between the particles is destroyed, and the fine sericite is hydrolyzed. Therefore, a better flotation index can be obtained.

(3) Collecting agent dosage test

The ratio of fixed octadecylamine to kerosene was determined by sorting the total amount of 5:1 collectors collected at 240, 300, 360, 420, 480 g/t. The test results show that as the amount of collector increases, the concentrate grade gradually decreases, while the recovery rate first increases and then stabilizes. Considering that only one roughing operation has been carried out, the test point with higher recovery rate is selected under the premise of ensuring the concentrate grade, that is, the total amount of collector is 420g/t, and the concentrate grade is 6.20%. The rate is 58.12%. In the pulp value test 2.4 slurry pH test test, sulfuric acid was used as a adjusting agent to adjust the pH value of the slurry to change the surface properties of sericite. The test results are shown in Table 4.

It can be seen from the data in Table 4 that when the pH value is 3.0, the recovery rate reaches a maximum of 63.49%, so the pH value of the flotation slurry is determined to be 3.0.

(4) Inhibitor dosage test

When the tailings are ground by a rod mill, the quartz coexisting with the sericite in the tailings is affected by the iron ions, and the buoyancy is better under acidic conditions, and the water glass can strongly inhibit the iron ions and the quartz activated by the aluminum . To achieve the purpose of separating it from sericite, while water glass also has the function of dispersing slime. To this end, the amount of the inhibitor water glass was tested.

It can be seen from the test results that the addition of water glass is beneficial to improve the concentrate grade. As the amount of concentrate is increased, the concentrate grade first increases and then decreases, and the recovery rate decreases. Considering the grade and recovery rate, 200g/t is selected, and the amount of inhibitor water glass is 6. At this time, the concentrate grade is 6.40%, and the recovery rate is 63.49%.

(5) Process test

On the basis of the above tests, in order to improve the concentrate grade, that is, to improve the quality of the product sericite, a rough selection, a sweep selection, and a two-stage selection process test were carried out on the tailings. The test flow is shown in the figure, and the test results are shown in Table 5.

The test results show that after one rough selection, two selections, and one sweeping, the concentrate grade is reached, which meets the requirements of 7.86% and 22.40% of the sericite first grade product; the recovery rate is reached, and the recovery rate through closed-circuit test is expected. It will be improved; at the same time, the grades of China National Mine 1 and Middle Mine 2 meet the requirements of sericite secondary and tertiary products respectively; the total recovery rate of sericite is 65.84%. The test achieved satisfactory indicators.

Figure 2 Determined test procedure

Note: dosage of drug g/t

Third, the conclusion

(1) By analyzing the multi-element, ray 1X diffraction and particle size of the flotation tailings of Xincheng Gold Mine, it can be seen that there are abundant sericite resources in the flotation tailings. The recovery of sericite from tailings is a comprehensive utilization project of “three wastes”, which is in line with China's industrial policy and achieves the unification of economic, environmental and social benefits.

(2) The key to recovering sericite technology is to find a collector with high selectivity for sericite. By comparing the recovery effects of different collectors, it is finally determined to use octadecylamine and kerosene as collectors. They are 350, 70g/t.

(3) By analyzing the crystal structure and surface characteristics of the mica minerals, it is known that flotation of sericite in an acidic environment is more effective and selective. Sulfuric acid was used as the adjusting agent in the research process. When the pH value of the pulp was obtained, the concentrate content obtained by flotation was 3.0K ₂ O 6.40% and the recovery rate reached 63.49%.

(4) The selection of effective inhibitors is also crucial for the recovery of sericite. The effect of water glass dosage on flotation was studied experimentally. The final determination of 200g/t was the optimal amount of water glass.

(5) The tailings can be obtained by one rough selection, two selections, and one sweeping process, and the recovery rate is K ₂ O7.86%.

22.40% of sericite concentrate meets the requirements of sericite first-class products and can obtain grade II and grade 3 sericite concentrates with grades of 6.69% and 5.25% respectively; the total recovery rate of sericite reaches 65.84%. index of.

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