# Dewatering: Thickening, Filtering, CCD, Water Treatment & Tailings Disposal

Dewatering: Thickening, Filtering, CCD, Water Treatment & Tailings Disposal 2017-03-23T09:42:05+00:00
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## Acid Neutralization Potential (4 replies)

OberstGruppen
1 year ago
OberstGruppen 1 year ago

Does someone knows if possible determine the Acid Neutralisation Potential (ANP) reported in ABA tests from % CaO of a sample, like the Acid generation potential (AGP) from sulphides in a sample?

Maya Rothman
1 year ago
Maya Rothman 1 year ago

It is not clear to me if the source of your % CaO is reported from actual ANP titration data, or if it is a result from some other method (e.g. total Ca reported as % CaO from XRF). ANP and AGP data are typically reported as tons CaCO3/kt material, or equivalently, kg CaCO3/t material. If your data represent ANP reported as % CaO, then this can be converted to units of CaCO3. The value will be larger when reported as CaCO3 because CaO has a CaCO3 effectiveness of 179%. Both CaCO3 and CaO consume 2 mol H+ per mol solid. For example, if you have 2% CaO, this is equivalent to 20 kg CaO/t. Multiplying 20 kg/t by the atomic ratio of CaCO3/CaO (1.79) gives 35.8 kg CaCO3/t. If on the other hand, your CaO data represent a different type of analysis (such as total elemental content), then this calculation will likely over predict the actual ANP.

OberstGruppen
1 year ago
OberstGruppen 1 year ago

Let me explain better: If I have a tailings sample mixed with cement, and if I know the % S-2 and % CaO, Can I calculate the AGP and ANP for this sample analytically (No tritation lab)?

The % S-2 and % CaO is taken from ICP and XRD reports.

Carl Jenkins
1 year ago
Carl Jenkins 1 year ago

It depends on the mineralogy and the response of the minerals to the test method used. Generally CaO from whole rock analysis would not be a good estimate of ANP, in this case, unless it is in the form of un-reacted lime and calcite. If there is gypsum or other non-acid neutralizing calcium mineral is present ANP would be biased high. I recommend ASTM E1915 methods backed by mineralogy to select the most appropriate method. Try measuring acetic acid soluble calcium to check your assumption.

Maya Rothman
1 year ago
Maya Rothman 1 year ago

I see now the Ca is indeed present as CaO and therefore could assume it is reactive. Based on this information, you could perform several back-of-the-envelope calculations. The ANP (kg CaCO3/t) could be estimated from the % CaO as I described above. The AGP can be estimated by the traditional method of assuming all sulphide-S is present as pyrite (AGP, kg/t, = % Sulphide-S x 31.25). Then you can estimate the overall net neutralization potential (NNP = ANP - AGP).