Feasibility of Copper Recovery from Spent Deposited Sludge of Transformer Oil (DSTO) for Industrial Applications

Due to fluctuating crude oil prices and a widespread desire to diversify Nigeria’s economy, recycling initiatives are preferred when addressing economic downfall. With increasing demands for metals and gradual depletion of non-renewable resources, there is a growing need to recover metals from secondary sources. The recycling from metal wastes is necessary as the cost of safe disposal of hazardous components is quite high compared to the amount of waste produced and limited storage capacity. Depending on the type and capacity, typical transformer oil contains 90–1485 kg of oil with a varying degree of recoverable sludge containing precious metals after degradation. In this work, leaching and solvent extraction techniques were adopted to treat spent DSTO obtained from Ayetoro III 300kVA Distribution Transformer having 245-kg oil weight capacity with 25 kg of recoverable combined sludge oil mixture. At optimal conditions, the leach liquor was accordingly treated and beneficiated to achieve 96.8% copper recovery efficiency.