Alluvial and Rock Gold Mines in Sierra Leone: Case Analysis

At the end of May 2020. a Sierra Leone gold mine customer found our company and wanted us to help him make a gold mine dressing plant.Our technical team has done many beneficiation projects in West Africa. Very familiar with the types of gold mines in Mali, Sierra Leone, and nearby countries.

Therefore, when we learned that the client ’s mining area was in Sierra Leone, we sent the client the pictures and videos of the original gold mine that he had done before.And confirm whether it is consistent with the minerals we have done. After the customer confirms, we started to analyze and design the gold mine for the customer.

Communication and analysis process

According to the mineral information feedback from customers, we understand that the customer’s primary ore is a mixture of alluvial gold and rocky gold.

1.Alluvial gold ore, containing mud, is too viscous. Because the customer did not understand this type of ore for the first time, he did n’t understand it and thought it had low viscosity, so at the very beginning, the customer wanted to use mobile tommel screen, centrifuges, shakers and other equipment to sort this type of alluvial gold.

2.In the rock gold ore section, the customer sent the ore picture (as shown below), according to the customer’s description of the rock gold ore. After analysis by our engineers, it is concluded that the rock gold mine belongs to iron conglomerate, commonly known as iron cap. Customer feedback that the rock gold is only about 100 meters away from the sand gold ore. For this type of rock gold, customers want to adopt the conventional beneficiation process, mainly including crushers, ball mills, centrifuges, shakers and other equipment.

Process Design

Processing capacity: 40TPH (customer requirements),

Specific process: (mixed processing of rock&alluvial) crushing-ore washing-sieving-small particles directly into the beneficiation part-large particles into the vertical shaft to continue crushing + washing-beneficiation (centrifuge + shaker)

Process line advantages

In this beneficiation process, in the beneficiation part, sand gold and rock gold use the same re-election production line, which reduces a large part of the cost compared to two production lines (one sand gold production line and one rock gold production line).

Difficulties of the project

In the process, we did not use the trommel screen mentioned by the customer but replaced it with a rotary scrubber. According to our knowledge and experience of the Sierra Leone gold mine, there are two reasons for not using the trommel screen for cleaning:

1. Sierra Leone is a kind of ore with high viscosity, which makes it difficult to scatter the minerals, which will cause the drum screen to malfunction.

2. Trommel screen is mainly used for sand-gold ore with little clay, such as river gold. The rotary scrubber is mainly used for rock gold with high clay content and high viscosity. The scraper inside it can wash this gold mine more effectively.

The above is the entire process of our technical team’s analysis, judgment and final design of the customized gold mine in Sierra Leone.