Optimisation of operating variables of fine coal flotation using a combination of modified flotation parameters and statistical techniques

Abstract Optimisation of flotation parameters using rate models is not a new concept. The kinetic model based on time recovery data, which uses the extra dimension of rate, has been in vogue since time immemorial for scaling up of lab data. Often, interpretation on the performance of a flotation circuit, based only on R ∞ (the ultimate recovery) and k s (the first-order rate constant of the component) may lead to wrong conclusions. In such cases, a modified flotation rate constant k mod defined as the product of R ∞ and k s , i.e., k mod = R ∞ k s and selectivity index (SI), defined as the ratio of the modified rate constant of valuables to the modified rate constant of gangue, can be used. An attempt has been made in this paper to optimize the batch laboratory froth flotation parameters of fine coal using the above two concepts, i.e., k mod and SI and statistical techniques. A flotation bank containing four Outukumpu cells was optimized using the results obtained from the lab study. The airflow number and the froth number were used as a basis for scale up. To gauge the performance of the froth flotation circuit, an efficiency parameter called the coefficient of separation or the CS was used. The yield from the flotation circuit improved, the froth ash reduced and the rejects ash went up.