TECHNOLOGY FOR PRODUCING LIQUID COMPLEX FERTILIZERS BY RECYCLING WASTEWATER GENERATED DURING THE PHOSPHATING PROCESS OF METALS

ABSTRACT

This article analyzes the composition of waste solutions formed during the phosphating of metals and wastewater from enterprises producing automobile reflectors, and considers the possibilities of obtaining liquid complex fertilizers based on their processing, the physicochemical properties of which have been studied. This approach is environmentally friendly and economically efficient, and allows the use of industrial waste to produce valuable products for agriculture. Currently, the main problems of industrial enterprises are to improve phosphating solution processes, reduce waste, save raw materials and fuels, develop measures to prevent waste in production, and implement new high-performance technologies, waste-free and low-waste technologies. Based on the types of waste studied, the composition and properties of fertilizers were analyzed.

АННОТАЦИЯ

В данной статье проанализирован состав отработанных растворов, образующихся при фосфатировании металлов, и сточных вод предприятий по производству автомобильных отражателей, рассмотрены возможности получения на их основе жидких комплексных удобрений, физико-химические свойства которых изучены. Такой подход является экологически безопасным и экономически эффективным, позволяет использовать промышленные отходы для получения ценных продуктов для сельского хозяйства. В настоящее время основными проблемами промышленных предприятий являются совершенствование технологических процессов фосфатирования растворов, снижение отходов, экономия сырья и топлива, разработка мероприятий по предотвращению отходов в производстве, внедрение новых высокопроизводительных технологий, безотходных и малоотходных технологий. На основе изученных видов отходов проведен анализ состава и свойств удобрений.

Keywords: industrial waste, phosphating solution, pH meter vacuum filter, alkaline wastewater, macro and micro elements.

Ключевые слова: промышленные отходы, фосфатирующий раствор, вакуумный фильтр pH-метра, щелочные сточные воды, макро- и микроэлементы.

Introduction

Solid waste from chemical industry enterprises is extremely diverse in terms of physical and chemical properties and environmental impact. The treatment of wastewater generated in production is considered one of the most problematic issues of our time and requires special attention. Water is one of the most important natural resources, but today, large quantities of harmful substances and toxic compounds are discharged into water bodies all over the world every day. As a result, the chemical composition of water is subject to negative changes, which in turn harms human health and the environment. The production of non-ferrous metals is one of the industries that consumes the most water. As a result of the neutralization of wastewater generated in metallurgical production and its discharge into open water bodies, several valuable useful components - chromium, zinc, nickel, iron, copper and other metals - are also lost along with wastewater. As a result of the conducted research, it was found that the complex separation of metals from wastewater is one of the most difficult problems to solve, which is associated with the presence of many components with similar properties, which makes their selective separation difficult. At the same time, research is being conducted to improve the phosphating solution processes aimed at using these wastes  to further extract valuable metals by purifying wastewater from the main phosphating solutions and returning them to production. Today, in the world, to further increase the productivity of agricultural crops, scientific research is being conducted to obtain fertilizers containing not only nitrogen, phosphorus and potassium, but also manganese, copper, zinc, cobalt, boron, molybdenum, which are important for the normal growth and development of plants. In this regard, special attention is paid to developing effective methods for obtaining nitrogen-phosphorus-potassium micro fertilizers, including a number of scientific solutions, including the study of the state of microelement salts, used catalysts, intermediate products and waste of non-ferrous metallurgy in fertilizer production conditions and their impact on the physicochemical properties of the finished product, and the creation of a technology for the production of nitrogen-phosphorus-potassium micro fertilizers using microelement raw materials.

Method

In this study, the waste solutions formed during the phosphating process of metals were separated from metal ions, hydro phosphate, phosphate, dihydrophosphate, chloride, and nitrate by neutralization method, using waste wastewater containing NaOH from automobile reflector manufacturing plants as a neutralizing reagent. Based on the results obtained, the possibility of using the new product as a fertilizer was evaluated. Initially, we determined the composition of both wastewaters during the sample preparation process by scanning electron microscopy (SEM), analysis. The wastewater was neutralized by determining the pH using a pH meter.

Results And Discussion

Waste with the following composition was used to obtain a liquid complex fertilizer by processing waste solutions generated during the phosphating process of metals (Table-1,2).

Table 1.

Chemical composition of wastewater generated after phosphating metals

Table 2.

Chemical composition of wastewater from automotive reflector manufacturing plants

The results of the study show that in this sample, the P content of the wastewater formed after phosphating metals is 15.64%, the phosphorus content is usually 8-16%, the pH of the wastewater was determined to be 2, and the pH of the wastewater from the automobile reflector manufacturing plant was determined to be 11-12. In laboratory conditions, the wastewater formed after phosphating metals was purified in three stages. The first wastewater was passed through a filter, where it was cleaned of large particles. In the second stage, heavy metals were precipitated. In the third stage, 100 ml of the precipitated water was filtered and 500 ml of the wastewater from the automobile reflector manufacturing plant was filtered. Both wastewaters were neutralized until the pH was 7. 2 ml of phosphorus wastewater was used in 140 ml of alkaline wastewater. Neutralized in a ratio of 2:140. The neutralized liquid fertilizer was filtered and sent for freeze-drying. X-ray analysis of the freeze-dried sample was performed

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Figure 1. X-ray analysis of freshly obtained liquid fertilizer

According to the results of the research, the fertilizer obtained from neutralized industrial waste contains 2.4% N, 16% P2O5, and 0.12% Zn, which significantly increases soil fertility. During the chemical processing process, the fertilizers were enriched with nitrogen, phosphorus, and potassium, which makes it possible to provide the necessary nutrients for plants. In addition, the resulting fertilizers provide environmental safety, as they are free from toxic substances and are beneficial for the soil and plants without harming the environment. Agricultural experiments have shown that fertilizers obtained from industrial waste allow for high crop yields. However, some difficulties may arise during the processing of industrial waste. For example, the composition of waste may be diverse, and some waste may be contaminated with toxic substances, which may complicate the processing process. Also, special technology and equipment are required for proper separation and processing of waste. At the same time, there are many positive aspects of industrial waste processing. This not only saves resources, but also helps protect the environment from pollution and ensure ecological sustainability. In the future, it is necessary to further simplify the processes of industrial waste processing, develop technological infrastructure, and more effectively separate waste.

Conclusion

Waste solutions resulting from the phosphating process contain important nutrients for agriculture. Recycling these wastes reduces environmental risks and creates the opportunity to obtain economically useful liquid complex fertilizers rich in microelements. The proposed technology is simple, inexpensive, and suitable for industrial scale implementation. The technology of obtaining fertilizers from local industrial wastes is an environmentally friendly and effective method, which is very important for increasing soil fertility and obtaining high yields in agriculture. This technology allows saving resources, protecting the environment, and increasing economic efficiency through the recycling of industrial wastes. Therefore, it is necessary to expand the recycling of industrial wastes and further develop this process. In the future, it is important to develop new technologies and methodologies to increase the efficiency of industrial waste recycling.

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