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Optimum Leach Density (1 reply and 1 comment)

2 months ago
Charlie 2 months ago

What is the typical % solids you would generally run a CIL circuit at? Thicker will result in more retention time but does it leach gold or silver as effectively? Any negative impact on carbon?


2 months ago
JohnnyD 2 months ago
1 like by Arnmax

I found 55% solids is best. If below 50% you will start sinking carbon. When density is too heavy say above 60% carbon and dissolved gold (pregnant solution) will have less contact - so retention time is a factor but always found with circuits I have run CIL or CIP 55% got the best results.

It could be ore and viscosity dependent. See below:

Marsden says of slurry density:

Leaching is usually performed at slurry densities of between 35% and 50% solids, depending on the solids’ specific gravity, particle size, and the presence of minerals that affect slurry viscosity (e.g., clays). Mass transport phenomena are maximized at low slurry densities; however, solids retention time in a fixed volume of leaching equipment increases as the density increases. In addition, reagent consumptions are minimized by maximizing slurry density, since optimal concentrations can be achieved at lower dosages, because of the smaller volume of solution per unit mass of material.

The rate of gold cyanide adsorption decreases with increasing slurry density. This effect is attributed to decreased mixing efficiency resulting from increased viscosity and decreased energy input per unit mass of slurry , physical blinding of the carbon surfaces and pores by fine ore particles or reduced solution–carbon ratio at higher slurry densities.

The mixing efficiency can also be reduced by increased slurry viscosity caused by changes in ore type rather than as a result of a change in slurry density. Ore types that produce high viscosity slurries also have a greater tendency to impair carbon performance; for example, by blinding of carbon pores with very fine particles. This effect is particularly evident when treating clay-bearing ores.

Anybody else?

1 week ago

I am working with an average of 42% solids, and we are facing a problem of carbon settlement in the bottom of the tanks. what are the other factors that can cause this problem

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