Fontes de amido aplicáveis à flotação de minério de ferro

Abstract

The performance of ten (10) starches from different botanical sources has been studied as depressant for iron minerals in the cationic reverse flotation of iron ore by means of bench flotation cell tests. The ore used was a friable itabirite with 100% in mass passing in the 0.210mm screen. This sample showed a high degree of quartz liberation ( 99.0% ) and the following contents: iron: 45.33%, silica: 33.15%, alumina: 0.40% and LOI: 1.10%. The botanical sources of starch studied were those whose physicochemical properties (amylopectin/amylose ratio, granule size, gelatinization temperature and suspension viscosity) approached the starch derived from corn. The gelatinization of starch suspensions has been performed with 10:1 starch:NaOH ratio, and the water used for dilution of up to 1% (w/v) was heated to 90°C. Flotation kinetics tests have defined the flotation tests time in 100s and based on the saturation curve of starch dosage, three points for addition were determined for comparative results: 500g/t, 1000g/t and 1500g/t. The results show that the starches tested can technically be used to replace corn starch. Furthermore, arrowroot, green banana, white sauce cassava starches and cassava scraps showed better performance than the conventional cornstarch in relation to the metallurgical recovery index, silica content in the concentrate and iron content in the float (tailings).