Introduction to Beneficiation Process of Placer Gold

I. Characteristics of Placer Gold Deposits and Gravity Separation Technology

Placer gold deposits, rich in gold, come in various types and are widely distributed. In these deposits, gold typically exists in a free state and has a significant density difference compared to sand and gravel. Based on this characteristic, gravity separation technology is an ideal choice for efficiently extracting gold from placer deposits.

II. Key Stages of Placer Gold Processing: Screening and Gravity Separation

Washing and Screening Stage

1. Washing plays a critical role in the placer gold beneficiation process. Its primary purpose is to efficiently separate gravel, sand, and clay, aiming to remove the fine mud attached to the gravel and the mixed gold-bearing sand. Typically, placer gold deposits contain a large amount of weathered clay, which forms cemented masses or sludge together with gold-bearing sand. Without prior disintegration, these cemented masses or sludge may be discarded along with waste rock during the subsequent screening process, leading to a reduction in gold recovery rates and unnecessary losses.

2.During the washing process, the first step involves preliminary rinsing with water to remove the fine mud and gold-bearing sand adhering to the gravel surface. Then, through the agitation of mechanical equipment such as vibrating screens, rotary scrubbers, and trommel screens, the sand cemented in cemented masses or sludge is gradually liberated. This series of operations aims to achieve effective separation of gravel, sand, and clay, ensuring that the clay and gold particles on the gravel are thoroughly cleaned. These washing operations not only improve the beneficiation efficiency of placer gold but also enhance gold recovery rates and reduce resource waste.

Gravity Separation Stage

Gravity separation is the core step in the placer gold beneficiation process. Due to the high density of gold, its appropriate particle size range (generally between 0.074 mm and 2 mm), and the cost-effectiveness and simplicity of gravity separation, this method is the preferred choice. At this stage, gravity separation equipment such as jig machines, shaking tables, and gold sluices are widely used to effectively remove most of the waste rock and obtain concentrates rich in coarse gold.

1.Jig machines play a significant role in placer gold separation. When the specific gravity difference between minerals reaches 1.25 or more, and the ore particles are liberated, jig machines can effectively process placer gold with a lower particle size limit of 0.04 mm. Their simple operational process and high equipment capacity make them highly effective in the roughing stage of gold ore processing.

2.Shaking tables also have unique applications in placer gold separation. They are particularly suitable for processing minerals with finer particle sizes. The gold separation process is stable and reliable, with clearly visible ore bands and a higher concentration ratio compared to other beneficiation methods. Depending on the ore particle size, shaking tables are mainly categorized into coarse sand tables, fine sand tables, and slime tables.