Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction

Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction

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How to interpret the Oxygen Uptake Rate Testwork results for a sample (1 reply)

I
ichigo2785
9 months ago
ichigo2785 9 months ago

Hello, I found an old data set for an oxygen uptake rate test for a sample at 45% solids. pH was modified to 10 from 8 using lime addtion, NaCN addition was 0.1% w/v. Air was the gas sparged through and sample was prepared to P80 70um.

The test was completed at 0hrs, 1hr, 2hr, 3hr, 4hr, 5hr, 6hr and 24hr, with readings done at 1 minute intervals over 15mins at each hour set to ensure the reading is stabilized.

I found the absolute slope for each hour data set and then from 1 hour to the 24 hour data set i plotted the slope points on the y-axis and the hours as the x-axis resulting in an exponential trend curve.

Data set was as below

@0hr slope = 0.0089, @1hr = 0.0288, @2hr = 0.0251, @3hr = 0.0246, @4hr = 0.0221, @5hr = 0.0223, @6hr = 0.0197, @24hr = 0.0080

The exponential curve is y = 0.0285e^-0.054x, where x is in hours and y is in (mg/l)/min of the oxygen uptake rate in the sample.

How do I actually determine the specific oxygen uptake rate for this sample source in (mg/g)/hr. How would I go about using this testwork for the oxygen requirements in a leach circuit for example. 

Any feedback is greatly appreciated in advance.

J
Jorge
9 months ago
Jorge 9 months ago

First and foremost, you have to know the mineralogical composition of the sample because dissolved oxygen is consumed by cyanicides such as realgar, pyrrhotite, arsenopyrite and stibnite. A small fraction of dissolved oxygen is consumed by the gold dissolution reaction, but it is necessary to increase the level of dissolved oxygen in the leaching tanks. The injection of air or oxygen is a good alternative. In order to determine the oxygen uptake to have to take samples of cyanide solution to estimate the gold dissolution and record the level of dissolved oxygen. The data is useful to estimate the gold dissolution and the dissolved oxygen. The slurry should content 25 percent solids and the cyanide addition should be 0.5 g/l, it can be higher if you want to evaluate the effect of cyanide addition. 


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