Determination of influence of pH on reaction mixture of ferritation process with electromagnetic pulse activation on the processing of galvanic sludge

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.

Influence of aeration rate and method of process activation on the degree of purification of zinc-containing waste water by ferritization

“…The data of structural analysis of sediment samples correlate well with the results of electron microscopy of ferrite sediment samples [21]. They showed the presence of crystals of irregular spherical shape in the pore space.…”

“…A significant drawback of existing technologies based on hydrophase ferritization is the implementation of the process at temperatures above 75 °С, which requires significant energy costs. In [20], it was shown that an alternative to thermal hydrophase ferritization is the activation of the process by electromagnetic pulse discharges at a process temperature of about 20 ° C. The course of the process of hydrophase ferritization is significantly influenced by the ratio of the concentration of ferrum ions and other heavy metals extracted from the solution [21]. At the same time, the cleaning efficiency largely depends on the pH value of the solution, the temperature and duration of the phase formation process [18].…”

Determining the rational parameters for processing spent etching solutions by ferritization using alternating magnetic fields

“…A feature of the proposed method of processing the etching solution is the AMF activation of the ferritization process. At the same time, the energy efficiency of the process of treating spent solutions is significantly increased since electricity consumption decreases by more than 40 % compared to thermal activation of the process [18]. The results of this work strongly suggest that AMF activation does not impair the degree of extraction of iron ions from the reaction mixture compared to traditional thermal activation.…”

“…The disadvantages of hydro-phase ferritization are high energy consumption since it is carried out at temperatures above 75 °C [17]. Paper [18] shows that an alternative to thermal hydro-phase ferritization is the activation of the process by alternating magnetic fields (AMF activation) at room temperatures. The studies were conducted at a high amplitude of magnetic induction (0.3 Tl), which leads to significant cost of electrical energy to activate the reaction mixture during ferritization.…”

Influence of Technological Factors on the Formation and Transformation of Iron-Containing Phases in the Process of Ferritization of Exhausted Etching Solutions

“…The course of the ferritization process is influenced by a number of technological factors that determine the type of primary embryonic iron-containing structures, their formation, and further development with the formation of stable compounds with different particle sizes and shapes. Among these factors are the initial concentration of iron ions [29], the pH value [30], the temperature [31,32], the process duration [33], and the oxidizer (air oxygen) consumption [34]. In addition, the above factors can affect the formation of a certain modification of iron hydroxides and oxyhydroxides and their subsequent transformation into other more stable oxide compounds in an alkaline medium [35].…”