Temperature Influence in Cornstarch Gelatinization for Froth Flotation

Starches are widely used as depressant in froth flotation operations in Brazil due to their efficiency, increasing the selectivity in the inverse flotation of quartz depressing iron ore. Starches market have been growing and improving in recent years, leading to better products attending the requirements of mineral industry. The major source of starch used for iron ore is the cornstarch, which need to be gelatinized, by heat or sodium hydroxide (NaOH) addition, prior its use. This stage has a direct impact on industrials costs, once the lowest consumption of NaOH in gelatinization provides better control of the pH in the froth flotation and reduce the amount of electrolytes present in the pulp. In order to evaluate the influence if the temperature in the NaOH consumption gelatinization tests were carried out with temperatures ranging from 25 to 65 ° C, measuring the volume of NaOH. All tests were performed in triplicate. A linear model correlating the temperature and the NaOH need for the cornstarch gelatinization had been stablished. This model can allow mineral industries to optimize the NaOH amount used to prepare the depressant to be used in froth flotation. For example, the reduction in NaOH could easily reaches 480 L per ton of cornstarch when performing gelatinization with cornstarch solution at 35 ° C when compared to 25 ° C.