Study on recovery of silver from refractory manganese ore tailings

I. Introduction

Jining, Inner thick silver ore Wang silver ore refractory metal manganese silver, mine beneficiation plant using dip manganese sulfate - silver cyanide leaching beneficiation process, but the recovery rate is low, tailing still contains 120g / The silver around t, so exploring the way to further recover silver from the tailings is of great significance to the mine. In this study, the tailings were subjected to multi-element analysis of tailings, rock mineral identification, re-election shaker test, re-election spiral chute test, spiral chute concentrate sulphuric acid immersion manganese - cyanide immersion silver test, spiral chute concentrate chlorine Chemical baking - cyanide immersion silver test and other experimental research work.

Second, the nature of ore analysis ^[1]

(1) Multi-element analysis of tailings

The multi-element analysis of the tailings is shown in Table 1.

(2) Identification of rock and mineral

Indicates that the identified rock tailings: mineral tailings in a wide range of complex, mainly metallic minerals are: argentite (spiro silver sulfur), chlorargyrite, native silver, manganese ore, manganese hard, hematite , goethite (goethite water) and a small amount of limonite galena, sphalerite and pyrite. The gangue minerals are mainly quartz and calcite . Silver-containing minerals mainly exist in the form of fluorite ore, horn silver ore and natural silver. Other silver-containing minerals are extremely low in content and are not seen under the microscope.

According to the occurrence state and embedding characteristics of silver-containing minerals, it is indicated that the silver-bearing tailings are extremely difficult to beneficiated, and the refractory factors are as follows:

1 Silver is mainly present as silver-containing minerals, including silver minerals, silver ore, horn silver, and natural silver. The carrier minerals associated with silver-containing minerals are manganese minerals, hematite, limonite and quartz. These silver-containing minerals are often interspersed or encapsulated in carrier minerals in the form of inclusions, veins and veins. They are hard to dissociate.

2 Silver-containing mineral particles are fine, especially the inclusions are finer, and the largest one is around 20 μm. It is very difficult to grind such fineness.

3 continuous organisms are complex, almost all of the carrier minerals and between the silver-bearing minerals and the carrier minerals have a continuous body, and the continuous body particles are very small, which makes the selectivity of dressing very difficult.

4 The occurrence state and the embedding feature are very complicated. Minerals and continuum are often jagged, dog-shaped, staggered, harbor-like and dendritic adjoining, and the inclusion crystals contain inclusions of very fine particles of silver minerals. Big.

5 Colloidal silver-bearing ore is visible on the surface of manganese minerals. This silver-containing mineral is very difficult to dissociate from manganese minerals.

In summary, the mine is difficult to select.

Third, the shaker test

In order to explore the re-election effect on the tailings, a shaker test was carried out. The XZY-1100X500 grooved shaker was used with a stroke of 12 mm and a stroke of 350 times/min. The test procedure is shown in Figure 1. The test results are shown in Table 2.

It can be seen from the test results that the tailings can be sorted by a shaker to obtain a silver concentrate having a yield of 15% or more and a grade of 253.18 g/t.

Fourth, spiral chute beneficiation test

Considering that the processing capacity of the shaker is small, the floor space is large, and the processing capacity of the spiral chute is much larger than that of the shaker, and the spiral chute sorting test is carried out in consideration of future industrial production. A Ф400 spiral chute was used with a separation concentration of 32.6%. The test procedure is shown in Figure 2, and the test results are shown in Table 3.

It can be seen from the test results that after one sorting by spiral chute, a concentrate having a grade of 255.38 g/t and a yield of 15% or more can be obtained.

In the future production, the tailings can be swept, and the concentrate can be merged into the concentrate after the concentrate grade reaches 250g/t. The sweep concentrate can also be returned to the rough selection. Both methods can further improve the concentrate yield.

V. Spiral chute concentrate sulphuric acid immersion manganese - cyanide immersion silver test

The concentrate obtained from the spiral chute has a low silver content, which is similar to the original ore grade of the Jining thick silver deposit in Jining, and should be further sorted and enriched. In order to explore the adaptability of the concentrate selected by the spiral chute to the original process of the mine selection plant, the concentrate selected from the spiral chute was subjected to sulfuric acid immersion manganese-cyanide immersion silver test. In order to examine the effect of immersion manganese, the concentrate selected from the spiral chute was subjected to different grinding fineness immersion manganese test, different leaching time immersion manganese test, and different sulfuric acid dosage immersion manganese test using XJT-80 leaching agitation tank. In order to examine the effect of cyanide immersion silver, the XJT-80 type leaching agitation tank was used to test the leaching slag of sulphuric acid immersed slag with different grinding fineness cyanidation immersion silver and different leaching time cyanide immersion silver test.

According to each condition test, the best test conditions were used for the sulfuric acid immersion manganese-cyanide immersion silver process test. The test procedure is shown in Figure 3, and the test results are shown in Table 4.

From the test results, the treatment of the initially enriched spiral chute concentrate was not good by the existing process of the concentrator, and the cyanide leaching rate was only 35.91%.

Sixth, spiral chute concentrate chlorination roasting - cyanide immersion silver flow test

If the sample is pre-chlorinated and calcined, the silver bound to the manganese mineral is converted into the form of silver chloride, the separation of manganese and silver is achieved, and then cyanidation leaching is performed, which is advantageous for increasing the leaching rate of silver. The chlorination roasting is divided into medium temperature chlorination roasting and high temperature chlorination roasting. The medium temperature chlorination roasting is carried out at a temperature not higher than 1000 ° C to cause the silver chloride to volatilize and adsorb on the surface of the material particles; and the high temperature chlorination roasting is Calcined at a temperature above 1100 ° C, silver chloride is gaseous and escapes from the flue [2]. Obviously, it is reasonable to use medium temperature chlorination roasting here. For this purpose, a medium temperature chlorination roasting condition test was carried out.

(1) Chlorination roasting test

The test was carried out under different calcination temperatures and different calcination time conditions. The ore samples were calcined and then cyanated and leached, and the leaching rate was measured to evaluate the test results. The test results are shown in Table 5 and Table 6. The trend analysis is shown in Figure 4 and Figure 5.

The calcination condition test results show that the chlorination roasting temperature is between 650 °C and 950 °C, and the leaching rate increases with the increase of temperature. Above 850 °C, the leaching rate increases with the increase of temperature, and the calcination temperature is determined to be 850 °C; The time was increased, the leaching rate was lowered, and the baking time was determined for 30 minutes.
The factors affecting the leaching effect mainly include the amount of sodium cyanide and the leaching time. For this reason, the sodium cyanide dosage and leaching time conditions were tested. The test procedure is shown in Fig. 6. The results are shown in Table 7 and Table 8. The trend analysis is shown in Fig. 7. 8 is shown.

As the amount of sodium cyanide increases, the leaching rate increases. In order to reduce the cost of leaching operations and subsequent wastewater treatment operations, the amount of sodium cyanide should be minimized. The amount of sodium cyanide taken temporarily was 2.73kg/t; the leaching rate increased with the increase of leaching time. When the leaching time was 36 hours, the leaching rate reached 79.29%.

in conclusion

1. The tailings are initially enriched by a spiral chute, and a concentrate having a grade of 255.58 g/t and a yield of 15% or more can be obtained. The spiral chute concentrate is basically equivalent to the original ore grade produced at the original production site.

2. For the spiral chute concentrate, the original sulphuric acid immersion manganese-cyanide immersion silver process of the original ore dressing plant can not obtain good results, and the cyanidation leaching rate is only 35.91%.

3. The medium temperature chlorination roasting of the spiral chute concentrate is carried out. The results of the cyanide immersion silver test show that the leaching time is 36.29% at the calcination temperature of 850 °C, and the leaching rate is 79.29%.

references:

[1] Su Chengde, Zhao Libing. Experimental study on the selectivity of tailings in the Houwang silver mine in Jining, Inner Mongolia [R]. Tang Shan: College of Resources and Environment, Hebei Institute of Technology, 2007.

[2] Huang Lihuang. Chemical beneficiation [M]. Beijing: Metallurgical Industry Press. 1990.

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