【Mineral Processing Case】Guinea 6000TPD Gold Processing Project

01One. Project Background

In 2018, Xinhai Mining formally signed the contract of 4000tpd gold processing plant with the client, providing it with one-stop and customized mineral processing EPC+M+O service. Xinhai Mining pointed out that due to the presence of gold particles, some gold particles were lost in the process of sampling, sample preparation and reduction in the original geological exploration process. Therefore, it is necessary to take large samples and then adopt gravity separation, and the concentrates, medium ores and tailings obtained by the gravity separation for sampling and analysis respectively, and the adhesion of gold particles on the equipment surface during the sample making process shall be considered.

The rigorous attitude, accurate data and customized services of Xinhai Mining were greatly appreciated by the client. And the client also recognized Xinhai Mining's strong brand strength, customized mineral processing EPC+M+O service, advanced and reliable equipment quality and excellent customer service, which contributed to the partnership. Finally, Xinhai Mining only took 10 months (including 2 months of transportation and customs clearance) before the project was formally put into operation with considerable economic benefits.

In 2019, the client decided to expand the original 4000tpd gold processing plant and expand the production capacity to 6000tpd on the original basis. Based on the successful production practice in the first phase, the client chose Xinhai Mining for re-cooperation, and entrusted Xinhai Mining to provide one-stop, customized mineral processing EPC+M+O service for its 6000tpd gold processing project.

02Two. Project Introduction

Ore Properties: the ore of this project was mainly oxidized ore, 80% of the ore was powdery clay ore, containing granular gold. The average grade of the ore was 1.0g/t, the quality of impurities is very little, the gold was the only recoverable element, and the ore was easy to be separated.

Processing Capacity: 6000tpd

Xinhai Solution: a closed-circuit grinding and classification – gravity separation - gold extraction by cyanidation - desorption electrolysis, smelting - tailings treatment.

03Three. Xinhai Solution

1. Raw ore feeding

Most of the raw ore in this project was fine slime ore with fine particle size, which didn't need the crushing stage. The raw material can be directly fed to the raw material warehouse, or discharged to the raw material warehouse for storage, and then sent to the steel bin by the forklift truck. The material was fed into the belt conveyor by the belt feeder under the material bin, then sent to the ball mill for grinding.

2. Grinding, classification + gravity separation

The ore transported by the belt conveyor was sent to the ball mill for one stage grinding, the ore discharge of ball mill was sent to the jig by the slurry pump for gravity separation. The coarse concentrate obtained by the gravity separation of flowed automatically to the 6s shaking table for cleaning, the concentrate obtained by the shaking table flowed automatically to another 6s shaking table to get gold particles, the middlings and tailings obtained by the shaking table flowed automatically to the pump box, and then were pumped to the ball mill for grinding. The tailings of jig were sent to the cyclone unit by the slurry pump for one stage classification, the cyclone settling returned to the ball mill for re-grinding, the overflow flowed automatically to trash screen for removing impurity, and then was sent to two-stage hydrocyclone classification. The two-stage hydrocyclone (two groups of hydrocyclone) settling and part of the overflow was sent to leaching, other overflow flowed automatically to the thickener for enrichment.

3. Thickening, cyanide leaching

The underflow density of the thickener was concentrated to about 40%, which was pumped into the double impeller efficient leaching tank by the slurry pump for leaching and carbon adsorption. And the roots fan was used to fill the leaching tank with air, the NaCN was added at the same time to make the full reaction among slurry, reagent and air.

The gold in ore reacted with NaCN in alkaline environment to form gold cyanogen complex ion. The gold entered the solution and was adsorbed by activated carbon. During the production, the carbon was extracted in reverse and the saturated gold-bearing carbon was extracted by the No.2 leaching tank. The undersize pulp was returned to the No.2 leaching tank. The oversize gold-bearing carbon was sent to the carbon storage tank for washing the carbon by the hydraulic conveying. The clean saturated gold-bearing carbon was re-sent to the desorption electrolysis system for gold processing, and the gold sludge was smelted in the high frequency melting furnace to obtain the final composite gold.

4. Regeneration of activated carbon

After a few times of use, the activity of activated carbon was weakened, the adsorption capacity of gold was decreased. In order to recover its activity and ensure its recycling, it is necessary to conduct regeneration treatment on degold-deoxidized carbon. There were two regeneration methods of activated carbon: one was pickling regeneration, another was high temperature activation regeneration.

5. Tailings treatment

The cyanide tailings were transported to the tailings pond by slurry pump for precipitation. The tailings were stocked in the pond, and the clarified water was returned to the production pond for recycling, so as to realize zero discharge of production sewage.

04Four. Project Advantages

1. one-stop and customized mineral processing EPC+M+O service

From mineral processing test, mine design, equipment manufacturing and procurement, packaging and delivery, installation and debugging, worker training, production standards reached to the project management and mine operation, all links were contracted by Xinhai Mining. The one-stop, customized plant solution was featured with high efficient project construction, short construction period, put into production quickly.

Since the signing of the contract, Xinhai Mining only took 8 months (including 2 months for transportation and customs clearance) to realize the formal operation of the gold processing project.

2. Reasonable design solution and advanced process

✦ Strip mining. Because the ore was sand powder, there was no need blasting in mining, which was excavated by the excavator, and directly sent to the factory. It greatly reduced the mining cost.

✦ The price of concrete was expensive in Guinea, the cost of the same amount of concrete was about five times of China. In order to reduce the investment and speed up the construction speed, Xinhai Mining adopted combined steel structure (including the warehouse) for the above-ground part, the steel structure was totally pre-processed in China, which can be assembly, disassembly and movement flexibly after transported to the site with fast construction, low investment and beautiful shape.

✦ 80% of the ore were powdered clay ore, the raw ore contained 25%-30% water. On the one hand, Xinhai Mining solved the plugging and feeding problems of powdered clay.On the other hand, Xihai Mining adopted gravity separation + cyanide process, specially strengthened the gravity separation process and grinding process, that is, firstly recycled part of the gold particles in the gravity separation process, reduced the gold grade of entering the leaching operation, thereby reducing the reagent consumption, saving the production costs.

✦ The whole plant was built according to terrain, each building was relatively concentrated. The equipment configuration in each plant room of the concentrator considers the main pulp to realize self-flow as far as possible.

3. Environment protecting and environmentally friendly

✦ the leaching agent used in the project adopted the environmentally friendly leaching agent with low toxicity, reagent consumption and cost. At the same time, the indicators obtained by this leaching agent is the same as the sodium cyanide.

✦ The production drainage (thickener overflow tailings and water clarifying backwater) were returned back to the pool for recycling, so as to realize production wastewater zero discharge.

05Five. Project Result

At present, the Guinea 6000tpd gold processing plant project has been successfully put into operation, the whole plant operates steadily, the equipment quality is reliable, and the dressing index and economic benefits have reached the expectation. Xinhai's professional mineral processing service strength has also been affirmed by the project customer.

The Guinea 6000tpd gold processing plant has successfully reached the standard and put into operation within a short time, which not only fully reflected the strong ore dressing strength, professional customized solutions and thoughtful customer service of Xinhai Mining, but also laid a solid foundation for further cooperation between the two sides.

After the successful operation of this gold processing plant, the project company in guinea quickly started the construction of another 15000tpd gold processing project in 2019, and continued to the cooperation with Xinhai Mining. At present, the Guinea 15000tpd gold processing plant has entered the stage of installation and debugging.

From the first cooperation, to the second cooperation, and then to the third cooperation, this project customer has become a partner who has a deep partnership with us. The mineral processing plants undertaken by Xinhai Mining has become the model project examples in local.

In Africa, more than 100 mineral processing EPC+M+O projects undertaken by Xinhai Mining spread in Guinea, Tanzania, Zimbabwe, Sudan, Nigeria, Morocco and other countries, effectively promoting the development of African mining industry. In the future, we will continue to adhere to the comprehensive deepening of reform, in-depth promotion of Xinhai solution, spread the correct concept and method of mine construction, and effectively provide global customers with more perfect, professional mineral processing EPC+M+O service!