Denilson Costa

Abstract:

The human consumption of vegetable oils for food in Brazil is very large. However, this consumption causes the downside of not reusing the residual oil, once the vegetable oil, during the frying process, undergoes chemical reactions that modify its composition, increasing the amount of free fatty acids and generating by-products of oxidation reactions. Thus, the problem of this waste disposal arises, which is generally done improperly, going to the sewers of big cities. In the mineral industry, the fatty acids salts (soaps), from the non-ionizable thio compounds class are the anionic collector reagents most used in the non-sulfide minerals flotation process, especially oximinerals. Therefore, the main objective of this research is to evaluate the possibility of using the residual frying oil as a collector reagent in the ore flotation. The advantage of using it as a collector reagent is that a great part of the fatty acids present are free from glycerol, favoring, this way, the alkaline hydrolysis (saponification) reaction for the collector obtainment. In this work, variables that influence the reaction were evaluated, such as time of reaction, water/alcohol ratio, and oil/NaOH ratio. The storage time of the obtained collector (0, 15 and 30 days) was also evaluated. The collection efficiency of the reagent (particles hydrophobicity) was verified by microflotation tests in modified Hallimond tube with height extensor (when necessary) to avoid entrainment, using pure apatite, calcite and quartz. In order to obtain a reference value for the floatability, the tests results were compared to the results obtained using sodium oleate as collector reagent. The results show that the use of a collector reagent obtained via alkaline hydrolysis of residual frying oil may be an alternative to the collector reagents currently used in the mineral industry.