Complex mineral fertilizers: opportunities of manufacturing them from technogenic wastes

Complex mineral fertilizers: opportunities of manufacturing them from technogenic wastes

ABSTRACT:

Purpose of the research is to study the development of technological modes of producing nitrogen-phosphorus-containing mineral fertilizer from industrial wastes in experimental conditions. Granulometric and substantial composition of phosphorus sludge and cottrell dust, mineralogical composition and microstructure of industrial waste for mineral fertilizers production have been studied. It was found possible to produce qualitative ammophos from phosphorus sludge and cottrell dust in proportion 2/1, using decomposition by mixture of 30% aqueous solution ammonium sulfate and humic acid. Conducted experiments allow to design the technology for producing complex fertilizers. Harmful environmental impact of waste is lowered, also production costs of the new fertilizer are much lower than of the existing ones. Unlike the traditional method of ammophos production from phosphoric acid and ammonia, the offered method allows to produce the complex and assimilable fertilizer, containing phosphorus and nitrogen in optimum proportions.

KEYWORDS:

technogenic waste; phosphorus; nitrogen fertilizers; ammoniation

Introduction

Development of industry all over the world has made the problem of complex processing of technogenic industrial wastes and involving non-standard mineral resources in the production to be topical. Phosphorus production, widely demanded both in Kazakhstan and abroad, is an example. Its production is determined by formation of large technogenic wastes in the form of overburden rocks, slag, phosphogypsum, ferrophosphorus, phosphorussludge and cottrell dust. Only in Zhambyl oblast there have been piled up over 30 million tons of the above said wastes. At the International Congress on issues of mineral resources and metallurgy industry (Astana, January 2014) NursultanNazarbayev, President of Kazakhstan said that in the country there have been piled up over 30 billion tons of techno genic wastes, the significant part of them is toxical. He emphasized, that now techno genic wastes should be considered as a self-sufficient raw materials base. Today as a result of reductive electric melting of phosphate raw material only at Novo-Zhambyl phosphorus factory about 140-160 kg of cottrell dust are formed per one ton of manufactured yellow phosphorus. This cottrell dust in the form of suspension – cottrellmilk is discharged into evaporation basins. In addition to, on the territory of the former phosphorus factory in Shymkent there have been accumulated over 500 thousand tons of phosphorus sludge, the chemical and granulometric composition of which is characterized by complex inclusions of mineral components of charge and products of processing.

Research of scientists and manufacturers and laboratory analyses as well show, that these technogenic wastes are quite valuable recoverable resources for production of composite building materials, phosphorus and compound mixed fertilizers, containing phosphorus-potassium. Ways and technologies of production of ameliorant of potassicammophos gypsum, superphosphate, double superphosphate, carbamide-ammonia fertilizer (CAF), monoammonium phosphate (MAPh), ammophoson the basis of phosphorus-containing technogenic wastes are known. Modes of production are worked out and the main characteristics of final output are determined. Alongside with that, today there are no completely founded technologies of processing phosphorus- containing wastes into demanded products, containing nitrogen, phosphorus, potassium. The problem of complex recovery of wastes is not being solved. The offered technologies are imperfect, this explains the existence of non-decreasing volume of wastes. Therefore, all the known technological solutions did not find full-scale practical application. Thereupon, search of new possibilities of utilization of large-scale phosphor-containing recoverable raw material is still crucial.

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