PRELIMINARY STUDY OF THE KINETICS OF LEACHING COPPER POWDERS OBTAINED BY GRINDING CIRCUIT BOARDS OF COMPUTERS. EFFECT OF THIOSULFATE, CONCENTRATION AND TEMPERATURE

Today the society requires new technologies and equipment. This is because the society isbecoming more demanding of products and services, making that the amount of wastes both electric asfrom electronics, increases in an alarming way, being this kind of wastes difficult of recycling in an easyand economical way. The above is due to the complexity of these kind of residues and the lack ofadequate techniques of recovery, because these components are made with a variety of materials thatdifficult its primary separation. Some of these components are nowadays considered as ?urban miningresources? because the amount of metals present in these are quite attractive from economic point ofview, as is the case of copper, which is present in important amounts.The present work is related with the study of the effect of thiosulfate, concentration and temperature,over the rate of leaching of the copper present in the ground circuit boards of computers. It was used amesh 50 from Tyler series due to the good uniformity of particles obtained. Leaching was carried outin a glass reactor of 500 mL of capacity, mounted on a hot plate with magnetic stirring, coupled to a pHmeter to control of OH? concentration. The reagent for leaching is used, was the O2?S2O32-, andevaluating thiosulfate concentration was done in a range from 0.075 to 0.5 M, and the temperature rangewas from 289-338 K, to determine the global rate of leaching of copper. According the results found, itwas determined that under certain work conditions such as: temperature of 338 K, [S2O32-] = 0.5 M, pH= 10, 750 min-1, 5g of sample and 180 minutes of reaction time, it was possible to get up to 97.35 % ofrecovered copper. From the obtained results, it was plotted the metal concentration vs. time, getting so straight lines in certain time periods, with which was possible to calculate the experimental constant of rate, kexp; and besides was plotted the log [S2O3 2-] versus log kexp to determine the order of reaction that for this case was of n = 0.05 in the range of 0.075 to 0.5 M of S2O3 2- . To determine the activation energy of the system, Ea, it was used the Arrhenius equation, getting so an Ea = 17.4 kJmol-1 which is indicative of a control by diffusion or transport, for the reaction of leaching of copper.