A STUDY OF SULPHIDISATION-FLOTATION ON OXIDIZED COPPER ORE

• Main Author: ABIDIN - NIM : 22116015, ZAINAL
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/31879
• Institution: Institut Teknologi Bandung

<p align="justify">One of the concentration process of copper sulphide ore is flotation concentration, in which the process utilizes the different properties of mineral surfaces whether wettable or not. One of the problems in the flotation process is when the ore to be processed undergoes oxidation. One of the copper mines in Indonesia that uses flotation as the concentration process of the ore is PT Amman Mineral Nusa Tenggara (PT AMNT) that has operated in eastern Indonesia, precisely in Batu Hijau, Sumbawa Island. PT AMNT is processing oxidized copper ores with varying levels of oxidation in which the oxidation rate is expressed by comparison between acid soluble copper (ASCu) to Cu. There are some problems in the oxidized ore processing such as decreasing of copper recovery because of high ASCu content in the ore and this will cause the interaction between copper surface against collector (PAX) will not going well, as well as the potential to degrade the environmental quality as metal content (copper) in the tailings increases. Flotation application for oxidized ores is done with the addition of sulphidised reagents, but any addition of the reagents should be strictly controlled because if its dose is insufficient or overdose, it will cause the recovery of copper to decrease. Therefore, study about the effect of doses of sulphidizing agents to pulp chemical potentials need to be performed, so that the optimum condition of the flotation sulphidisation process can be determined which can produce a good copper recovery.<br /> <br /> In this study, sulphidisation flotation was performed on oxidized sulphide ores to determine the effect of sulphidation sodium hydrosulfate (NaHS) addition to pulp chemistry and copper recovery on the flotation process. Samples containing chalcopyrite and bornite as the source of copper with an oxidation level of 32.84% was milled using rod mill with 50% solid for 13.1 minutes to obtain P80 212 &#956;m. The product of the mill was then added with seawater up to % solid of slurry about 35% and the slurry was used as flotation feed. The flotation tests of oxidized ore were performed without sulphidisation and with sulphidisation. In sulphidisation-flotation, tests were performed using two schemes, i.e. the first based on the starting point of NaHS addition, and the second based on by means of addition of sulphidation reagent. For the first scheme, the flotation test was performed using sulphide oxide flotation (SOF) and oxide flotation (OF). In both flotation tests, the controlled potential sulphidisation (CPS) technique was used by varying the value of Es at -300 mV; -400 mV; -500 mV; and -600 mV in which each values of the Es was maintained for 1 min by the addition of NaHS. For the second scheme, a slug sulphidisation (SS) technique was applied by the SOF method in which the addition of NaHS was spontaneously performed with a variation of NaHS dose about 167.07 g/t; 190.87 g/t; and 245.93 g/t. The doses of NaHS were determined from the required dose on the SOF-CPS method to produce an Es of -300 mV; -400 mV; and -500 mV respectively.<br /> <br /> In the CPS technique of the first scheme, the optimum Es for oxidized copper sulphidisation was in the range from -400 mV to -500 mV. The SOF-CPS method resulted the highest Cu and ASCu recovery of 71.33% - 71.35% Cu and 36.47% - 37.35% ASCu. In OF-CPS method, the recovery of 70.43% - 70.46% Cu and 31.93% - 34.59% ASCu were resulted, whereas flotation without sulphidisation resulted recovery of 68.69% Cu and 29.64% ASCu respectively. Based on the experiment of the CPS technique on both sulphidation (SOF and OF) methods, it was concluded that high Es (-600 mV) would cause overdose of NaHS usage, so that the recovery resulted became low, even lower than without NaHS addition. Furthermore, high Es caused excessive reduction process and the dissolved oxygen to be low so that the PAX adsorption process on the copper mineral surface did not go well causing the copper recovery to be poor. At low Es, the resulted recovery of copper to be low especially the recovery of ASCu, because the low value of Es resulted in low quantity of &#119867;&#119878;&#8722; ions which would be formed so that it was unable to sulfidise the oxidized copper through the reduction reaction. In the second scheme, the SOF-SS method with a dose of 167.07 g/t was able to generate a Cu recovery that similar to the optimum condition in the SOF-CPS method in which the recovery achieved was 71.32% although the dosage of NaHS used was the same. The difference between the SOF-CPS and the SOF-SS aside from by mean of the NaHS addition was the chemical potential (Es) produced after NaHS was added, where 167.07 g/t NaHS in SOF-SS method produced Es -526 mV while SOF-CPS produced Es -300 mV. From the recovery of Cu on the SOF-SS and SOF-CPS methods, it was shown that the Cu recovery was independent of the length of conditioning time of NaHS addition but depended on the chemical potential (Es) of the pulp. It is also concluded that the use of SOF-SS method has the potential to increase the recovery of Cu with more economical reagent consumption.<p align="justify"> <br />