Abstract
This paper considers prospects for increasing the level of environmental safety of industrial enterprises as a result of the implementation of resource-saving technology of processing galvanic sludge using the ferritization method. The effectiveness of the use of electromagnetic pulse discharges for resource-saving activation of the ferritization process with the extraction of heavy metal ions from sludge (Fe, Ni, Cu, Zn) has been confirmed. The influence of key parameters of the process such as the pH value of the reaction mixture and the initial concentrations of metals in the solution on the quality of processing galvanic sludge by ferritization has been experimentally investigated. It was determined that with an increase in the pH value from 8.5 to 10.5 the residual concentrations of metal ions decrease to the values of 0.1÷0.25 mg/dm3 regardless of the total initial concentrations. It has been established that the technique of electromagnetic pulse activation ensures an adequate degree of extraction of metal ions of 99.9 %; it also has indisputable energy advantages compared to the thermal method: energy costs are reduced by more than 60 %. That indicates the suitability of purified water for reuse in galvanic production in terms of the requirements for the content of heavy metal ions in it. In addition, the structural studies of ferritization sediment samples have been carried out. The sediment is characterized by the maximum content of crystalline ferromagnetic phases of ferrite. It was established that an increase in the pH of the initial reaction mixture leads to an increase in the ferrite phase in sedimentation: at pH=10.5, phases were detected, which are characterized by a maximum ferrite content (exceeding 76 %). The proposed resource-saving ferritization process prevents environmental pollution, ensures efficient and rational utilization of raw materials and energy in the industry; it also makes it possible to obtain commodity products from industrial waste.
Highlights
The problem of man-made pollution is increasingly exacerbated every year and is becoming global
The result of the experimental studies is the devised technique of two-stage processing of sludge formed as a result of neutralization of galvanic production wastewater, its transfer to the liquid phase, and subsequent hydrophase fer ritization
Depending on the total concentrations of heavy metals in the reaction mixture in the range of 5÷20 g/dm3, sulfuric acid etching solution should be diluted by 3 and 10 times to transfer the sludge to the liquid phase, followed by its ferritization
Summary
The problem of man-made pollution is increasingly exacerbated every year and is becoming global. Every year in Ukraine, industrial enterprises accumulate about 1 million tons of these toxic wastes, which are practically non-neutralized and recycled. In Eastern Europe, the volume of these wastes reaches 15 million tons [2], When stored in industrial areas within the city zone, such sludge is a source of high man-made environmental impact. The reuse of materials removed from sludge could allow an enterprise to reduce the fee for the storage of hazardous waste, receive additional economic benefits from the sale of new products, and reduce the load on the ecosystem [4]. It is a relevant task to conduct studies aimed at removing toxic heavy metals from galvanic sludge enabling the minimization of formed sediment and the rational utilization of water, raw materials, and energy in the galvanic production system
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