TECHNICAL AND ECONOMIC ANALYSIS OF METHODS FOR PRODUCING PHOSPHORIC ACID UNDER THE CONDITIONS OF WESTERN SIBERIA

V. B. Buran

The development of phosphate-fertilizer production in one or another economic region depends on the organic combination of a number of factors: the capacity and effectiveness of the phosphate raw-material base, the economic potential, and the regional features of the economic region. In considering the conditions for establishing phosphate-fertilizer production in Western Siberia, it is necessary to provide an economic justification for methods of processing West Siberian phosphate raw materials, as well as raw materials from nearby East Siberian phosphorite deposits, taking into account the distinctive features of the West Siberian economic region.

It is known that the production of phosphatic fertilizers is carried out by three methods: 1) grinding phosphorites to obtain phosphorite meal; 2) the acid method for obtaining soluble fertilizers; 3) the thermal method for obtaining soluble fertilizers. The choice of production method is determined by the quality of the phosphate raw material, the availability of raw material for the production of sulfuric acid, and the capacity and effectiveness of the fuel-and-energy base. At the same time, phosphorite meal is a sparingly soluble fertilizer; it is produced only from karst phosphorites, whose phosphate substance is capable of dissolving in acidic soil solutions and in weak phosphoric acid.

World practice in the production of soluble phosphatic fertilizers gives preference to acid methods, since this method is the most fully mastered and does not require significant energy expenditures. In the USSR as well, the bulk of phosphatic fertilizers is produced by the acid method. In recent years the thermal method has been mastered ever more widely. This is promoted by a number of factors.

The production of phosphatic fertilizers, especially concentrated ones, in terms of technical and economic indicators depends on the economics of phosphoric acid production. In turn, the technical and economic indicators of phosphoric acid production are conditioned by the methods of obtaining it. The extraction method makes it possible to obtain high-quality and inexpensive acid when high-grade phosphate raw material is used. With the availability of cheap electric power, it becomes possible to carry out acid production by the thermal method, which, in terms of technical and economic indicators, is not inferior to the extraction method.

The possibility of joint exploitation of West Siberian and a number of East Siberian phosphorite deposits provides phosphate-

…the fertilizer industry of Western Siberia with phosphate raw materials suitable for processing by both the acid and the electrothermal methods (Belkino and Tamalyk phosphoconcentrate), as well as with raw materials suitable for processing only by the electrothermal method (Belkino karst phosphorite, Tamalyk and Obladzhan phosphorites, and, possibly, Verkhuzass phosphorite).

Laboratory experiments on obtaining phosphoric acid from Belkino phosphoconcentrate were carried out at NIUIF. They showed that phosphoric acid can be obtained with an increased consumption of sulfuric acid compared with the processing of Karatau phosphoconcentrate by 25%, and Kirov apatite concentrate by 38%. Moreover, the decomposition of Belkino phosphoconcentrate in all experiments was low and amounted to 24–26%.

The considerable consumption of sulfuric acid and the low decomposition of phosphoconcentrate in obtaining phosphoric acid by the acid method from Belkino phosphoconcentrate cause an increase in the cost of phosphoric acid production and in specific capital investments, taking into account those associated with the raw-material base.

The limited resources of sulfuric acid in Western Siberia have a negative effect on the technical and economic indicators of production of extraction phosphoric acid. The organization in Western Siberia of phosphate-fertilizer production using acid methods raises the problem of expanding the supply of sulfuric acid to the region’s industry. This problem can be solved either through the development of sulfuric-acid production in Western Siberia or through the import of sulfuric acid from economic regions that have reserves of sulfuric acid.

At present, Western Siberian sulfuric-acid production is based on sulfur pyrite imported from the Urals and, to some extent, on wastes from a number of industrial enterprises in Western Siberia. On the whole, the sulfuric-acid balance in Western Siberia is deficient. A substantial reserve for eliminating the sulfuric-acid deficit is the expansion of the processing of the Salair sulfide polymetallic ores and barites of the Ursk deposit, located northwest of the city of Salair. The developing Western Siberian oil-refining industry cannot be regarded as a significant source of sulfuric-acid raw material, since its development is connected in the future with the processing of low-sulfur Western Siberian oil.

Consequently, the resources of sulfuric-acid raw material in the West Siberian economic region are limited. And the development of phosphoric-fertilizer production in this region must be considered with allowance for supplies from other economic regions of either raw material or sulfuric acid. Calculations carried out in this direction using data from TsNIITEneftekhim¹ showed that the lowest costs for supplying Western Siberia with sulfuric acid can be obtained by expanding sulfuric-acid production in Western Siberia on the basis of imported oil-refining sulfur from the Volga region. The reduced national-economic costs for the production of sulfuric acid in Western Siberia on the basis of oil-refining sulfur imported from the Volga region are 39.5% lower than on the basis of pyrite concentrate imported from the Urals.

¹ According to data from TsNIITEneftekhim, with an annual capacity of an oil refinery of 12 million tons of oil, the capacity for elemental sulfur production will be 100 thousand tons; capital investment, 1 million rubles. (Prospective Oil Refineries of the USSR. TsNIITEneftekhim. Moscow, p. 67, 1966).

The calculation performed for the techno-economic indicators of the production of extraction phosphoric acid under the conditions of Western Siberia from Belkinsk phosphoconcentrate showed the following. The cost of phosphoric acid, calculated per 1 ton of \(P_2O_5\) from Belkinsk phosphoconcentrate in Western Siberia (Tashtagol, Novokuznetsk, Myski, Kemerovo, Kamen-na-Obi), is 97.6–106.3 rubles; specific capital investments are 378.7–411.8 rubles; and reduced national-economic costs are 173.4–188.6 rubles. A comparison of the techno-economic indicators of producing extraction acid from Belkinsk phosphoconcentrate in Western Siberia and from Karatau phosphoconcentrate in Kazakhstan (Dzhambul) indicates that the variants are equivalent. Thus, according to data from NIUIF, the cost of 1 ton of \(P_2O_5\) in extraction phosphoric acid obtained by processing Karatau phosphoconcentrate under the conditions of Dzhambul is 106 rubles; specific capital investments are 383 rubles; and reduced national-economic costs are 182.6 rubles.^2) However, according to the same data, processing Karatau phosphorites under the conditions of Almalyk is less expensive: the cost is 67.4 rubles, specific capital investments are 323 rubles, and reduced national-economic costs are 132 rubles. The latter indicates that orienting phosphoric-acid production in Western Siberia toward Belkinsk phosphoconcentrate is associated with an increase in the cost of its production, compared with acid production from Karatau phosphoconcentrates under the conditions of Almalyk, by 30–39% in terms of reduced national-economic costs.

Under the conditions of Western Siberia, where there is currently an acute shortage of sulfuric acid and a powerful fuel-and-energy base exists, production of phosphoric acid by the thermal method is of particular interest. Adoption of the electrothermal method makes it possible to substantially expand the raw-material base of phosphate-fertilizer production, since in the production of phosphoric acid, along with primary phosphorites, secondary phosphorites from Siberian deposits may be used. At the same time, the use of secondary phosphorites from the Belkinsk deposit helps improve the techno-economic indicators of phosphoric-acid production, since their development is characterized by more favorable techno-economic indicators compared with the development of Belkinsk bedded phosphorites.

The techno-economic indicators of thermal phosphoric-acid production are determined by the techno-economic indicators of phosphorus production, since 89–92% of the acid cost is formed by phosphorus costs, and 90–96% of capital investments are associated with phosphorus production. In this connection, in those economic regions where the most favorable techno-economic indicators for phosphorus production are ensured, the most advantageous economic conditions are created for the production of thermal phosphoric acid.

In the east of the country, electrothermal sublimation of phosphorus can be carried out on the basis of phosphorites from Kara-Tau (Kazakhstan); the Belkinsk deposit (Western Siberia), the Tamalyk, Obladzhan, and Seibinsk deposits, and phosphorus-containing wastes from the beneficiation of complex ores of the Beloziminsk deposit (Eastern Siberia). For the indicated deposits, a comparison of the techno-economic indicators of phosphorus production has been carried out (Table 1).

The organization of phosphorus production in Western Siberia from phosphorites of the Belkinsk and Tamalyk deposits, according to techno-economic—

^2) Fedorenko N. P., Tsipina E. I. Techno-economic comparison of phosphoric-acid production methods. Chemical Industry, No. 9, 1964.

technical-and-economic indicators is practically not inferior to the production of phosphorus from Karatau phosphorites. Thus, the cost of producing phosphorus in Western Siberia is lower than in Kazakhstan owing to the availability of cheap electric power. However, capital investments in Western Siberia are higher. The two indicators offset one another when calculating reduced national-economic costs; the latter are approximately the same for both economic regions.

Table 1

Technical-and-economic indicators of phosphorus production in Western Siberia, the Volga Region, Kazakhstan, and Eastern Siberia

Note: 1) The cost has been recalculated taking into account the valuation of costs for ferrophosphorus in terms of phosphorus.

The best technical-and-economic indicators in the production of electrothermal phosphorus in the east of the country are achieved through the commissioning of Beloziminsk apatite concentrate. Second place in terms of technical-and-economic indicators is occupied by phosphorus production based on Karatau phosphorites; third place—by production based on local phosphate raw materials in Western Siberia. At the same time, it should be noted that, despite the favorable technical-and-economic indicators of phosphorus production when processing Beloziminsk apatite-

concentrate, the development of the resources of the Beloziminskoe deposit is conditioned by the obtaining not of apatite raw material, but of a number of target products. In addition, the very favorable technical and economic indicators for the production of phosphorus from Beloziminsk apatite concentrate are to a certain extent due to the unjustifiably low cost and low capital investment in concentrate production, which are taken only for the beneficiation stage, without taking account of the costs of ore mining. What has been said confirms the important significance of the Belkinskoe and Tamalykskoe deposits of phosphate raw material for the creation of phosphate-fertilizer production in Western Siberia.

Table 2

Technical and economic indicators for the production of thermal phosphoric acid in Western Siberia, the Volga Region, Kazakhstan, and Eastern Siberia

The indicated relationship of the technical and economic indicators for phosphorus production in the economic regions considered is also maintained with respect to the production of phosphoric acid—thermal

(Table 2): the most favorable techno-economic indicators are characteristic of the production of thermal phosphoric acid under the conditions of Eastern Siberia on the basis of Beloziminsk apatite concentrate; the techno-economic indicators for the production of phosphoric acid on the basis of Belkinsk and Tamalyk phosphorites in Western Siberia and Karatau phosphorites in Kazakhstan are practically equivalent.

Comparing the techno-economic indicators of phosphoric acid production under Western Siberian conditions by the acid and thermal methods, the following may be noted. The stated national-economic costs are approximately the same. This is explained by the fact that the production cost of phosphoric acid by the thermal method is 8–18% lower than by the acid method, while the specific capital investments are 13–20% higher. At the same time, if conversion costs under the acid method amount to 7.59–7.75 rubles, under the thermal method they amount to 39.77–45.6 rubles. This ratio of conversion costs is associated with the high energy costs of the thermal method, which are 18–20 times higher than under the acid method of phosphoric acid production.

The structure of specific capital investments is also not the same. The share of direct capital investments in the main and auxiliary facilities of a chemical plant for phosphoric acid production within total capital investments per unit of capacity is 13.1–18.9% for the extraction method, and 30.1–39.0% for the thermal method. Specific capital investments in the main and auxiliary facilities of a chemical plant under the thermal method are 2.2–3.3 times higher than under the acid method, while associated investments are 5–28% lower. Up to 99% of the associated capital investments of the acid method are due to capital investments in associated production of phosphate raw material, sulfuric acid, auxiliary materials and their transportation, while investments in the energy base do not exceed 1%. Under the thermal method, 57–85% of associated capital investments are formed through investments in the energy base.

Consequently, a significant part of the cost and capital investments under the thermal method is formed by the costs of the energy component, whereas under the extraction method it is formed by the costs of the sulfuric-acid component. For the prospective period in Western Siberia, given the shortage of sulfuric acid, the most expedient option for the development of phosphatic fertilizer production should be considered the mastering of the thermal method of phosphoric acid production, since the West Siberian economic region is characterized by a highly efficient fuel-and-energy base. In addition, the calculation performed indicates a reduction in the labor intensity of producing thermal acid, in comparison with extraction acid under Western Siberian conditions, by 12–21%, which is extremely important for the West Siberian economic region, where a relative shortage of labor is felt.

A serious advantage of the electrothermal method under Western Siberian conditions is the possibility of bringing into economic circulation, along with bedded and karst phosphorites from West Siberian and nearby East Siberian deposits of phosphate raw material, since under the extraction processing method it is not possible, owing to the strict requirements of the extraction method for the quality of phosphate raw material, to use karst phosphorites in the production of phosphoric acid.