Slowly soluble phosphate glasses are a promising material for new environmentally safe fertilizers. The kinetics of the dissolution of phosphate glasses used for the development of fertilizers was studied.Modern nature management is impossible without application of mineral elements, because ions of potassium, magnesium, calcium, phosphorus, boron, and trace elements are irrevocably withdrawn from soil together with agricultural products. Existing mineral fertilizers have a number of principal drawbacks connected with their crystal structure and constant composition. These fertilizers are easily washed away and weathered from the soil, which gives rise to extreme workloads on soil microorganisms and root systems of plants. Annual world production and application of fertilizers reaching 400 million tons is not only prodigal, but also environmentally dangerous, as no less than 50% of fertilizers goes to subsoil waters and is weathered, causing environmental pollution.The cardinal way of overcoming these drawbacks is to abandon traditional crystalline fertilizers and to develop essentially new highly effective fertilizers based on glassy amorphous materials. Glass is one of the most promising among these materials because of its favorable physical and chemical properties and feasibility of processing.In the early 1980s, phosphate glasses were used to develop a new generation of fertilizers [1]. These fertilizers of the prolonged action are based on glassy potassium, magnesium, and calcium metaphosphates doped with microelements. Their preparation was based on long-term experience in the field of development of optical glasses and ion-exchange processes.As a result of these studies [1, 2], a new type of glassy fertilizers (AVA) was developed; their high efficiency and environmental cleanliness are due to the high-temperature synthesis of phosphate systems, quenching of the structural state of the components in the form assimilable by plants, and their variable composition providing easy adaptation to regions of use, to types of soils, and to the kind of crops.The rate of dissolution of such glasses depends on their chemical composition. Glass components, K, Ca, and P oxides, are nontoxic. Such glasses provide egress of the required compounds from the glass into the environment. The dissolution of a glass in water is accompanied by a chemical reaction between the glass and water, which results in cleavage of the >P3O3P< bonds and passing of phosphate ions into solution. Metal ions contained in the glass together with P 2 O 5 pass simultaneously into the solution at a rate determined by the rate of the glass dissolution. The soluble phosphate glass can be used for delivering fertilizers with a specified intensity and substances for protection of plants.According to published data [3,4], the dissolution of phosphate glasses involves several steps: selective passing into a solution (leaching) of cations within the framework of internal diffusion and hydrolytic degradation of the anionic skeleton. However, the most import...
The solution of the sludge utilization problem and yield increase at processing plants have great importance today all over the world. Disasters associated with the tailings dams failures have madeus develop technologies of tailings sludge utilization as a commercial product, reducing the environmental damage on the regions of mineral extraction. This research aimed to provide new data, methods and an analytical approach to solve the saponite sludge accumulation problem on mining enterprises with silicate coagulant to increase the rate of cycle water clarification for the enrichment process and the recycling of sludge to reduce its hazardous effect. Samples were taken in the deposit located in the north of the European part of Russia, where diamond bearing ore contain montmorillonite minerals, mostly saponite, which is considered to be a perspective secondary product. The content of this mineral in the sludge is above 20 wt.%. Saponite is a clay mineral with the general chemical formula (Ca,Na)0.3(Mg, Fe2+)3(Si, Al)4O10(OH)2·4H2O. The mineral has high adsorption, ion exchange, and catalytic and filtration properties; due to the developed diffuse layer, saponite particles are highly stable in an aqueous medium—the resulting suspension is highly stable and has slow sedimentation. During the research, a positive effect on the sedimentation process of clay saponite particles was established, due to the introduction of a coagulant containing 70% tricalcium silicate, at a dosage of 2 g/dm3 coagulant; the degree of purification of water containing the saponite clay suspension is 99%. The condensed sediment after the thermal drying and with the limestone addition can be used again as a coagulant or secondary product with enhanced properties;therefore, the sludge will be processed, and not stored.
The very complex nature of hydrocarbon raw materials, such as crude oil, and all kinds of reactions and mutual interactions of all its components and phases with each other and with steel equipment (base metals, alloying elements and inclusions), as well as the applied temperatures and pressures in refining processes, in addition to the technical conditions of the steel equipment and storage and transportation conditions of crude oil, all this makes it almost impossible to completely dehydrate and desalinate crude oil, which is the real cause of most of the inevitable problems. Taking into account high corrosion rates, premature failures and the growing number of accidents and emergency stops, researchers face a challenging task and a great responsibility to provide a more comprehensive understanding of corrosion, and proposing deeper corrosion mechanisms that take into account the role of multiphase metal components, which are not less important than the influence of other corrosive components.
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