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high rate thickener water balance (1 reply and 1 comment)

5 months ago
jovanifirebird 5 months ago

Do you think it is possible to get an overflow of 1% solid by weight with the right water balance requirement in high rate thickeners or in a gold processing plant? I believe not. Why I am asking you this is, because the plant I got engaged got an overflow of 1% solid by weight almost everyday. What I thought is, if they had been using the correct water balance calculation, it difficult to get a 1% sbw. It is so diluted. Is that possible?


Jorge Ganoza
5 months ago
Jorge Ganoza 5 months ago

If the solids content in the thickener overflow is 1% w/w, there is something wrong. The solids content should be less than 1% w/w. 

  • Try to review the thickener design, maybe the samples used to get information for the design are different to the current ore treated in the plant.
  • Review the thickener size diameter and the feed slurry density considered in the design
  • Check the feed rate. It should be similar to the design
  • Other key aspect to consider is the presence of clays. A clayed material has a very slow settling rate and the overflow could be dirty.
  • You can determine the solids content in the lab and compare the results with the mass balance.
4 months ago

Agree with Jorge's comment - (the % solids is way too high) 1% solids is 10,000 ppm. Settling tests where there is effective settling usually achieve supernatant much lower that 1% (e.g. 100 ppm) unless there is a significant amount of fine particles feeding the thickener (e.g. if the feed to the thickener is 50% solids and it contains 2% minus 10 microns (as an example), one would expect the thickener overflow to contain elevated TSS. If the fines cannot be removed, and/or the there is no other alternative, this suggests a settling aid may be required - this could be tested on thickener overflow samples: (a) try a slight increase in lime, which often aids settling; (b) a cationic flocculant. If a Zeta Meter were available to you, determining the particle charge (positive? or negative?) and the magnitude of the charge (Zeta Potential) would provide insight whether to use a anionic/cationic/flocculant.

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