High-sulfide gold ore refers to a certain type of gold ore that contains 20%-30% gold and is encapsulated by sulfide (mainly pyrite). Since most of the gold in high-sulfur gold mines exists in the form of sulfide-coated gold, when the direct leaching process is adopted, the consumption of gold leaching agent and the production cost of gold leaching will increase, and the recovery efficiency of gold is not high. Therefore, it is best to use gravity separation, flotation or flotation cyanidation process. The following is an analysis of specific beneficiation tests and introduces four commonly used high sulfide gold ore process methods for high sulfide gold ore.
Gravity beneficiation is not only suitable for placer gold beneficiation, but also for the traditional and most basic method of high sulfide gold beneficiation.
Commonly used gravity separation equipment includes shaker, spiral chute, jig, centrifugal concentrator, etc. It is recommended to use a centrifugal concentrator for high-sulfur gold beneficiation, because the centrifugal concentrator has a small area and low energy consumption. It can recover difficult-to-handle materials and minerals, improve the recovery rate of minerals, separate inclusions and remove slime. In order to reduce the loss of gold in the tailings and increase the gold recovery rate as much as possible, two roughing and one concentrate treatment can be used. The intermediate ore is returned to the roughing operation for post-processing, which can maximize the gold recovery rate.
First, determine the best grinding size and centrifugal force through the ore grinding fineness test and the centrifugal force field test. Then, the intermediate ore, which uses two roughing operations and one type of concentration, is returned to the roughing operation for reprocessing for high sulfide gold beneficiation. The processing flow chart is shown in the following table. Through centrifugal gravity separation, gold can be enriched better. The final gold concentrate grade is 54.9g/t, and the gold recovery rate reaches 85%. The process is relatively simple, but usually the recovery rate is not as good as the flotation method.
Flotation is one of the commonly used methods for sulfide gold beneficiation. Because flotation can maximize the enrichment of gold in sulfide concentrates. According to the properties of high sulfide gold ore, the sulfide suppression flotation process is selected.
The sulfide suppression flotation process prioritizes the recovery of gold, aiming to maximize the recovery of gold and sulfides. Pre-determined grinding size, chemical system and metal processing test. Under the most suitable process parameters, gold is recovered through a rough separation and two concentrated flotation processes. Then, the crude sulfide concentrate obtained through the rough processing process is subjected to a flotation process, with one roughing, one concentration and two removals to recover the sulfide. Finally, the comprehensive recovery of gold and sulfide was realized. The gold concentrate grade is 56.1g/t, and the recovery rate reaches 88%. The processing flow is shown in the following table.
Mixed flotation is one of the beneficiation methods of high sulfide gold. According to the nature of the ore and the results of gold processing experiments, the coarse grinding and mixing flotation-regrinding-sulfide separation process can better recover gold.
Choosing the right grinding fineness can help avoid over-grinding, which is the primary prerequisite for reducing grinding costs and increasing recovery rates. Therefore, the rough grinding test is very important to determine the best particle size before the separation process. After determining the optimal coarse grinding particle size, a flotation test is carried out to determine the type, dosage, dosing point and dosing method of the flotation reagent.
Under the best process parameters, the mixed concentrate of gold and sulfide is obtained by the process of one roughing-two selections-flotation. Before the next flotation operation, the obtained mixed concentrate is subjected to a fine grinding test process to determine the best particle size. On this basis, gold concentrate and sulfide concentrate are obtained by one roughing-two concentrates-one cleaning flotation method. The gold concentrate grade is 57.67g/t, and the recovery rate is 93.08%. This process realizes the comprehensive recovery of valuable sulfides, while effectively recovering the gold in the ore.
The symbiotic relationship between gold and sulfide in high-sulfur gold mines is close, and most of the gold is wrapped in sulfide, so the recovery rate of gold directly leached is extremely low. In addition, the consumption of gold leaching reagents is large, so the cost of directly leaching the raw ore is higher. Therefore, high sulfide gold cyanide is not suitable. Considering comprehensive factors such as beneficiation test results and production costs, the flotation roasting cyanide leaching process is finally determined as an alternative process.
On the basis of determining the optimal grinding size, the most suitable process is determined by a flotation test as a roughing-a cleaning-a concentration process. The gold-bearing minerals in the high sulfide ore are enriched into the concentrate through flotation, and then slaked lime and additives are added to the flotation concentrate, and after being thoroughly mixed, it is roasted. The firing temperature is usually controlled at about 650°C. The sulfide is removed by firing, so that the coated gold is exposed, and at the same time, porous and high-permeability calcined sand that is favorable for leaching is obtained.
The roasted sand after roasting and desulfurization is dissolved and stirred according to a certain solid-liquid ratio, and cyanide or an environmentally friendly gold leaching agent is added for stirring and leaching. After the leaching is completed, the gold concentrate can be obtained by filtering, washing and drying operations. The gold concentrate grade is 76.25g/t, and the recovery rate reaches 89%.
These four gold mineral processes can better recover gold from high sulfide gold ore. Considering the gold concentrate grade and gold recovery rate, the mixed gold flotation process and the flotation-roasting-cyanide leaching process are ideal indicators for gold processing. However, it is necessary to fully consider the specific process selection according to the nature of the ore and the investment in the gold ore dressing equipment.
