PLANT FOR COMBINED PRODUCTION OF PHOSPHATE SALTS AND POTASSIUM SULFATE

Our № 10364 ε-α-

The present invention relates to chemical technology, in particular to the installation for combined production of phosphate salts, for example dicalcium phosphate and/or tricalcium phosphate, and potassium sulfate.

Phosphate salt and potassium sulfate are widely graphical products on modern market mineral fertilizers. The first are used for production of various phosphorus fertilizers, and potassium sulfate itself alone is potassium nekhlorsoderzhashchee fertilizer. Therefore development of effective and high-profitable equipment for their production is represented actual theme modern chemical technology.

On present moment known sufficiently large amount of works revealing production of phosphate salts by means of decomposition of phosphate ore with the use of hydrochloric acid. So, for example, in copyright certificate su1470663 described is production of dicalcium phosphate as a result of decomposition of phosphate material 35% - hydrochloric acid at feed rate of the last 0.24 - 0.60 kg/h per 100 g phosphorite in aqueous suspension at temperature of 35 - 40 with. from documents su842083 and su994457 known production of complex fertilizers from phosphorus-containing raw material decomposition of its hydrochloric acid, subject of field for this purpose diluted hydrochloric acid (1 - 4%). However in all these operations not considered source of hydrochloric acid, and not invention discloses a equipment for process.

The most close to declared invention is plant for production of phosphates, unit containing hydrochloric leaching, apparatus for preparing solution for neutralization, neutralization unit liquid phase and precipitation of phosphates, filter for isolating phosphates, apparatuses for washing and drying phosphates (cm. Jafarov and. 2. Production of precipitate. Moscow, 2 yr - in "food industry", 1975, with. 5 - 57). Known installation is designed for producing dicalcium phosphate, used as fodder phosphate, from bone meal by hydrochloric leaching. Unit of hydrochloric leaching is made in form of reactors (matseratsionnykh apparatus), in series combined in stages (group) or battery cocurrent flow of hydrochloric acid and products of hydrochloric leaching, unit and neutralization of liquid phase and deposition of phosphates is made in the form of several reactors (pretsipitatorov), combined in series with each other to provide for continuity of the process and provided with capacity for collection and averaging composition of phosphate pulp, apparatus for preparing solution for neutralization is apparatus for preparation of milk of lime, which allows well possible to process high quality phosphate raw material (bone cake) without using additional devices for separation of solid and liquid phases at stage of leaching of (semisolid organic wastes are removed from reactors of vacuum suction). However from - due to absence of similar devices fed processing of phosphate ore, especially ores low quality, solid wastes of leaching the litter reactors unit neutralization and precipitation of phosphates, and then and is product itself - phosphate salts. This limits efficiency and field known installation. In addition, for installation operation is required external source of hydrochloric acid - imported hydrochloric acid, required amount of which not always accessible technically and logistically, the latter increases the cost of production of phosphates, and so the same limits its field.

Therefore the aim of was in creation of installation for decomposition of phosphate raw material, including unit necessary for process of hydrochloric acid, and which enables to obtain simultaneously phosphate salt and potassium sulfate.

The task was thus by means of development of the new installation for combined production of phosphate salts and potassium sulfate, including

•unit of production of potassium sulfate and hydrochloric acid from potassium chloride and sulfuric acid, which contains furnace for production of potassium sulfate, apparatus for producing prediluting hydrochloric acid and unit for preparing of hydrochloric acid for leaching, and

•unit of production of phosphates from phosphate raw material, which contains unit hydrochloric leaching, apparatus for preparing solution for neutralizing, connected with it pipeline main line unit neutralization of liquid phase and precipitation of phosphates, successively installed behind it and connected transport mains filter for isolating phosphates, washing unit phosphates and apparatus for drying phosphates,

the between unit of hydrochloric leaching and a unit of neutralization of liquid phase and precipitation of phosphates is located apparatus for separating solid and liquid phases after leaching, which is connected with them pipeline main lines, and furnace for production of potassium sulfate through the outlet gas is connected by pipeline with apparatus for production of prediluting hydrochloric acid, and the latter is connected pipelines through unit for preparing of hydrochloric acid for leaching with unit hydrochloric leaching.

Main effect of the present invention consists in the possibility of obtaining phosphates from phosphate raw material of different quality due to optimization of modes and conditions of production, optimal for this raw material, at the simultaneous production of on plant of valuable mineral fertilizer - potassium sulfate. In addition installation according to the invention allows to reduce essentially the costs of transportation of required raw material and to optimize power consumption.

The proposed according to the invention installation is designed for producing the following phosphates: dicalcium phosphate, tricalcium phosphate, their mixtures, and also mixtures dicalcium phosphate, tricalcium phosphate with minerals, containing phosphates, for example with ftorappatitom. For production of phosphates is used phosphate ore (phosphorite, apatite) with content of pentooxide phosphorus more than 20%. The claimed plant allows to obtain commercial product (phosphate) - dry phosphate salt using for leaching (decomposition of phosphate ore) hydrochloric acid, produced by the plant. In proposed plant production of hydrochloric acid with use of sulfuric acid results in production of valuable low potassium fertilizer - potassium sulfate. Number of prediluting hydrochloric acid, required for leaching, is directly proportional to volume production of potassium sulfate, and concentration of its can reach 33% by mass, which allows to select optimal modes of leaching depending on the type and quality of phosphate raw material, in particular, to choose an optimal concentration and consumption rate of acid for most types of phosphate raw materials. Introduction of plant unit of producing potassium sulfate and hydrochloric acid from potassium chloride and sulfuric acid, which contains furnace for production of potassium sulfate and apparatus for producing prediluting hydrochloric acid provides realization of production of potassium sulfate on plant and production on it hydrochloric acid for leaching, and introduction of unit for preparing of hydrochloric acid for leaching allows preparation of required amount of hydrochloric acid of given and optimal for raw material concentration. Presence in unit obtaining phosphates from phosphate raw material apparatus for preparing solution for neutralization and unit neutralization of liquid phase and precipitation of phosphates allows to produce required qualitative and quantitative composition phosphate salts in product phosphate, also as and introduction of apparatus for separation of solid and liquid phases after leaching. The apparatus for separating solid and liquid phases after leaching, filter for isolating phosphates, washing unit phosphates provide high product purity, and apparatus for drying completes production of phosphates in commercial form. Due to said combination of features, the proposed device provides preparing commercial phosphates from raw material of different qualitative and quantitative composition of at continuity process and its high efficiency.

So, in contrast to known level of technology invention allows to create the first time installation for production of commercial phosphates from phosphate raw material of different quality due to optimization of of modes and operating conditions of conformably to raw material or type of final product using for leaching phosphate raw material prediluting hydrochloric acid, produced in the plant, and to obtain new for such plants and valuable product - potassium sulfate. In addition for production of hydrochloric acid in the inventive device is used sulfuric acid and potassium chloride which are available and cheap raw material, to conduct realization of said installation in industrial scale.

Figure 1 diagrammatically illustrates design and operation of proposed installation.

Installation for production of phosphate salts and potassium sulfate has unit obtaining phosphates in, which includes unit hydrochloric leaching 4 with inputs by phosphate of raw material and hydrochloric acid, apparatus for separating solid and liquid phases after leaching 5, unit neutralization of liquid phase and precipitation of phosphates 6, apparatus for preparing solution for neutralizing 7, filter for isolating phosphates 8, washing unit phosphates 9, apparatus for drying phosphates 10, and also unit of production of potassium sulfate and hydrochloric acid and, which contains furnace for production of potassium sulfate 1, apparatus for producing prediluting hydrochloric acid 2 and unit for preparing of hydrochloric acid for leaching 3. the output of the unit hydrochloric leaching 4 is connected by pipeline with input of apparatus for separation of solid and liquid phases after leaching 5, output apparatus 5 by solid phase is the output of the installation by solid containing waste, and its output by liquid phase is connected by pipeline with input of supplying of liquid phase leaching unit neutralization of liquid phase and precipitation of phosphates 6, input by solution for neutralizing unit neutralization of liquid phase and precipitation of phosphates 6 is connected by pipeline with output of apparatus for preparing solution for neutralizing 7, unit output of neutralization of liquid phase and deposition of phosphates 6 is connected by pipeline with input of filter for extracting phosphates 8, output of which by filtrate is the output by liquid containing waste installation, and the output of which is connected fosfatu transport vehicle through washing unit phosphates 9 with apparatus for drying phosphates 10, output of apparatus 10 is the output of by commercial product installation, furnace for production of potassium sulfate 1 has inputs by potassium chloride and sulfuric acid and output of by product, and the output of the furnace 1 by gas is connected by pipeline with apparatus input for production of prediluting hydrochloric acid 2, apparatus for producing prediluting hydrochloric acid 2 also has input for water supply, and its output is connected by pipeline with input unit for preparation of hydrochloric acid for leaching 3, the second input of which is the input of water, and the output unit for preparation of hydrochloric acid for leaching 3 is connected by pipeline with input of hydrochloric acid with unit hydrochloric leaching 4.

Installation operates as follows. Potassium chloride and concentrated sulfuric acid is in required amount in furnace 1, where as a result of high-temperature reaction is formed potassium sulfate, derivable from it along conveyor, hot gases, containing gaseous hydrogen chloride fed from the furnace in apparatus for producing prediluting hydrochloric acid 2. in apparatus 2 gases are cooled, hydrogen chloride absorbed water, fed into apparatus 2, and accumulates in apparatus 2 in the form of hydrochloric acid. When hydrochloric acid high concentration it pumped along pipeline unit for preparation of hydrochloric acid for leaching 3. in the unit 3 is dilution of hydrochloric acid to preset concentration and accumulation of hydrochloric acid preset concentration in amount, required for installation operation. Simultaneously in apparatus for preparing solution for neutralizing 7 mixing with water of water neutralizing agent and is production of solution for neutralization of preset concentration (milk of lime, suspension calcium carbonate and T. U.).

Phosphate raw material the required degree of dispersion, for example in the form of phosphorite flour, in required amount is sent to block hydrochloric leaching 4, simultaneously there is fed hydrochloric acid of required concentration and in specified amount from the unit 3. in the unit of 4 under action of hydrochloric acid is transition phosphates in solution and formation on outlet pulp, containing mainly monocalcium phosphate, soluble chlorides metals and solid impurities. Incoming from the unit 4 in apparatus for separating solid and liquid phases after leaching 5 pulp is divided into solid phase, be removed from installation as solid waste, and liquid phase in the form of acid solution mainly containing monocalcium phosphate and soluble impurities. Arriving in unit neutralization and precipitation of phosphates 6 acid solution phosphates and soluble impurities is mixed with solution for neutralizing, reported in required amount from apparatus for preparing solution for neutralizing 7, at NII to increase the pH of mixture up to required values is conversion of monocalcium phosphate in dicalcium phosphate (and at selection of corresponding mode in tricalcium phosphate or in mixture phosphates), which in is precipitated. Produced in unit 6 phosphate slurry comes to filter for isolating phosphates 8. filtrate from filter 8 mainly in form of solutions of chlorides of calcium, magnesium and other impurities is collected and removed from installation as liquid waste, and solid residue dicalcium phosphate (or preset other phosphate), is directed to washing unit phosphates 9, where is washed water and repeatedly is filtered or is divided phase (contaminated flushing liquid st is drained as liquid waste), and then is supplied to apparatus for drying phosphate 10, from which output product thus obtained is - phosphate. Gases, released in the blocks hydrochloric leaching 4 and neutralization and precipitation of 6, are subjected to absorption and cleaning in corresponding apparatus (on figure not shown).

At change of composition used phosphate raw material in the unit for preparation of hydrochloric acid for leaching 3 proceeding from concentrated prediluting hydrochloric acid prepared optimal for given raw material concentration of hydrochloric acid, which in required amount, proportional number and quality raw material is supplied to unit leaching 4, simultaneously in apparatus for preparing solution for neutralizing 7 is preparation of neutralization solution required concentration and amount of, in this force are provided optimal conditions and modes of production of phosphates.

Solid wastes, obtained with apparatus for separation of solid and liquid phases after leaching 5, utilization. Liquid wastes with filter for extracting phosphates 8 and with washing unit 9 are fused in sea, and at no such possibility are subjected to processing in solid waste or in commercial products known methods, for example by evaporation.

Potassium sulfate, obtained in furnace 8, is realized as valuable fertilizer separately or in composition of mixed or complex fertilizers.

Units, apparatuses and units of plant are realized known way. So units hydrochloric leaching 4 and neutralization of liquid phase and deposition of phosphates 6 can be realized in the form of one or several successively installed reactors (here and further on reactor - this reservoir with mixer with branch pipes input liquid phase and for discharge of pulp, branch pipe or hatch (tray and conveyor) for feeding dispersed phosphate raw material or neutralizing solution), reactors may be combined into stages or battery, including by principle of cocurrent flow, with supply of raw material, or accordingly neutralizing solution in the first or in several reactor of cascade (battery) unit 4 or 6. units 4, 6 can be realized based on much sectional reactors (extractors). Obligatory condition continuous operation of the installation in this case the presence of in units of 4, 6 storage reactor - reservoir with mixer or accumulating container without mixer, in which is collection and averaging of pulp of leaching or phosphate pulp before separation of respectively in apparatus 5 or on filter 8. as storage reactor can be used the last reactor cascade or last section much section reactor. In cases of supply of phosphate raw material or neutralizing solution in several reactors (sections) units 4, 6 may contain device distribution respectively phosphate raw material or solution for neutralizing by reactors, which for example, may be made in the form of tank (reactor), which has one input and several outputs, connected by pipelines with reactors, and monitoring and - measuring and control equipment.

Apparatus for preparing solution for neutralization of 7 may be made in the form of mixer (reactor with mixer), in which dosed preset values of solid neutralizing agent and water.

Unit for preparing hydrochloric acid for leaching 3 can be implemented in the form of several storage vessels, vessel with mixer (reactor), equipped with pumping, control measuring and control equipment, combined pipelines.

Apparatus for separating solid and liquid phases after leaching 5 can be made in form traditional devices for separation of (separators, filtering apparatus), for example in the form of filter - press.

Filter for isolating phosphates 8 also is realized traditional manner in form of filtering apparatus of various types, for example filtrpressov, including including washing unit (revolving, belt filters). So in using as filter 8 belt filter washing phosphate by supply of water on part of belt filter. For filtration and washing phosphates can be used drum vacuum filter and - T. U.

Washing unit phosphate 9 and apparatus for drying phosphates 10 also are realized known way. So in the form of separate unit for washing can be used reservoir with mixer and settling. Also can be used drying apparatuses boiling layer, drum, tunnel drier and other structure for washing and drying traditional in production of precipitate.

As furnace 1 can be used muffle furnace, heated gas flame, and other types of furnaces. Apparatus for producing prediluting hydrochloric acid 2 can be implemented in form of series-connected with each other coolers, for example of the adiabatic type, sequence absorbers, for example in the form of of the absorption column, collector - accumulator prediluting hydrochloric acid.

For pumping and metering liquid and dispersed media, pulps in installation is used raised control - measuring and pumping equipment, and for delivery of raw material, removing products and waste can be used conveyors, pneumatic transport or other equipment.

In force contained above the proposed device may be realized and used in industry.

More detail invention explained then presented in examples, which but does not applied or any limitations of the volume of claims.

Example 1

Furnace with a heated roof 1 unit of producing hydrochloric acid A loaded dry potassium chloride in the amount of 51 kg/h and the reaction zone was dosing sulfuric acid concentration of 98% in the amount of 35 kg/h. Process was carried out at the temperature of 400 theoretically, the chlorid potassium sulfate in an amount of 62 kg/h, which is bezkhlornym sodium fertilizer. Released hydrogen chloride in the form of gas sent on absorption of water, where three successive columns absorption occurred formation of 78 kg/h 31% hydrochloric acid. After dilution with water to 12% hydrochloric acid in amount of 200 kg/h sent in unit of production of phosphates from phosphate raw material IN.

Unit hydrochloric acid leaching 4, representing cascade reactors with mixer, filed phosphate material in the form of phosphate flour fraction 1 - 2 mm. Phosphate flour in the amount of 44 kg/h sent the first reactor from cascade reactors decomposition of ore. To there of the filed 12% hydrochloric acid in amount of 200 kg/h. Process was at temperature 60 theoretically and atmospheric pressure. From the system reactors pulp, containing phosphates 4.9% in terms of phosphorus pentoxide and 4.2% insoluble sediment, filed on filtration. In process of filtering insoluble precipitate is they separated, and solution phosphates filed in unit neutralization and precipitation of phosphates 6, which is a cascade reactors with stirrers. At temperature 60 theoretically and atmospheric pressure by means of feeding reactors cascade 33% water pulp calcium carbonate from apparatus for preparing solution for neutralization of 7 in the amount of 30 kg/h was partial neutralization reaction mass. The achieved was to increase the pH in reaction zone to 3.5, due to which phosphates salespeople in insoluble in water form. Pulp from reactor with content of 4.1% phosphates in terms of phosphorus pentoxide sent filtration, where they separated solid phosphate salt and in the amount of 26 kg/h dry product in the form of wet cake sent washing water to content of chlorine ions not more than 0.1%, and then drying to moisture content of 5%. Solution 18% - CSOs calcium chloride separated in process of filtering sent on utilization of.