How to Improve Gold Recovery in a Gravity Circuit

Gravity circuits remain one of the most cost-effective methods for recovering coarse and fine gold in both alluvial and hard-rock operations. However, many operations leave significant gold on the table due to suboptimal equipment setup, feed preparation, and circuit design. This guide walks through the key factors that affect gold recovery and how to address them.

1. Feed Preparation: Size and Density Matter

The single biggest factor affecting shaking table performance is feed preparation. Tables are most efficient when feed material is classified into narrow size fractions. Feeding a wide size range — say, 0–2 mm — results in fine particles being swept off the table before they can separate, while coarse particles crowd the deck and reduce residence time. For best results, split your feed into at least two fractions: a coarse fraction (0.5–2 mm) and a fine fraction (0–0.5 mm), and process each on a table tuned to that range.

2. Water Flow Optimisation

Wash water volume is a variable that must be balanced for each ore type and feed size. Too much water flushes light and heavy particles together off the tailings end of the table, destroying separation. Too little, and the concentration bands become poorly defined.

3. Stroke and Frequency

The differential, asymmetric motion of a shaking table is what drives mineral separation by creating differential velocities between particles of different densities. MST Shaking Tables feature easily adjustable stroke mechanisms that allow rapid on-site tuning without stopping production.

4. Feed Rate and Pulp Density

Overloading a shaking table is one of the most common causes of poor recovery. When the feed rate exceeds the table's capacity, the deck becomes crowded and the heavy mineral layer cannot stratify properly. Reduce feed rate until you see visible stratification — a dark, well-defined gold and heavy mineral band along the high side of the deck, with light gangue washing off the low end. Pulp density at the feed box should typically be 30–50% solids by weight for fine gold duty.

5. Circuit Configuration: Rougher-Cleaner Setup

For maximum gold recovery and concentrate grade, consider a two-stage table circuit. A rougher table makes a bulk upgrade of the gravity concentrate, maximising recovery but accepting some dilution. The rougher concentrate then feeds a cleaner table, which produces a high-grade, smeltable gold concentrate. The MST ST-range is specifically designed for this duty — the ST-300 and ST-700 are well-suited for rougher duty in larger circuits, while the ST-80 and ST-140 excel as cleaner tables producing direct smelting-grade product.

Need Help Optimising Your Circuit?

MST has over a decade of experience helping mining operations around the world improve their gravity gold recovery. Whether you are designing a new circuit or troubleshooting an existing one, our team can assist with equipment selection, circuit design, and on-site commissioning support. Contact us to discuss your operation.