TECHNOLOGY FOR PROCESSING LOW-SULFIDE GOLD-QUARTZ ORE

Abstract

The relevance of the research is caused by the necessity to acquire new knowledge about the enrichment of gold-bearing ores and the need to develop the resource base of the Russian Federation, namely involve subsoil use objects in economic circulation. The purpose of the study is to study the processing of low-sulfide gold-quartz ore using an integrated technology for the enrichment of mineral raw materials. Object: gold ore raw materials with an average gold grade of 11,88 g/t. The silver content is negligible – 2,43 g/t. The main ore minerals in the sample are pyrite and pyrrhotite. The average content of these minerals in the ore, according to mineralogical and X-ray diffraction analysis, was about 6 % (in total). The main rock-forming minerals of the original ore are: quartz – 60,1 %; quartz-chlorite-mica aggregates – 3,8 %; carbonates – 7,1 %. Methods. The research methodology was based on the theoretical foundations of mineral processing. The study of the material composition of the ore, and enrichment products, was carried out using chemical, assay, thermal, spectrometric methods, as well as atomic emission spectrometry and other methods. The study of washability was carried out by the methods of gravity and flotation enrichment, namely: GRG test, stage test of the Institute TOMS (Russia) (determination of the optimal size of ore grinding and the number of enrichment stages), modeling of gold extraction in the grinding cycle, determination of the optimal degree of grinding, study of the choice of flotation reagents, study of the kinetics of the process and the implementation of a complex of technological studies. Results. It was found that the gold recovery when performing the GRG test was 72,75 % with a total concentrate yield of 1,34 % and a content of Au 664,78 g/t. At the same time, the gold content in the tailings was 3,29 g/t. A stage test showed that for ore processing only by gravity technology, it is advisable to use a two-stage scheme. The first stage is in the grinding cycle with the ore size of 60–70 % and the second stage – with the final size of the discharge of the classification 90 % size of –0,071 mm. Centrifugal separation, as a free gold recovery operation in a grinding cycle, works efficiently. A concentrate with a gold content of 2426 g/t was obtained with an output of 0,31 % and an extraction of 63,74 %. The enrichment of the first stage tailings crushed to 90 % size of –0,071 mm at the KC-CVD concentrator (modeling) made it possible to extract gold into a total gravity concentrate (KC-MD+KC-CVD) of 87,25 % with a concentrate yield of 22,63 %. The gold content in the tailings was 1,97 g/t. The results of gravity and flotation concentration of the original ore indicate the feasibility of using a combined gravity-flotation technological scheme. In a closed experiment of the initial ore beneficiation according to the gravity-flotation scheme at a natural pH of the pulp (without adding acid), the following products were obtained: gravity concentrate with a gold content of 2426 g/t at a yield of 0,31 % and an extraction of 64,06 %; flotation concentrate (after the II cleaning) with a gold content of 122 g/t with a yield of 2,90 % and recovery of 33,01 %; the total gold recovery in the gravity-flotation concentrate was 94,07 % with a yield of 3,21 % and Au content of 345,87 g/t, the gold content in the flotation tailings was 0,72 g/t.

Keywords

• gold
• enrichment
• technological research
• flotation
• gravity
• modeling
• concentrate
• tailings
• extraction