SU943213A1 - Method for granulating phosphogypsum - Google Patents

Description

one

This invention relates to methods. drying with simultaneous granulation of pulverized raw materials, in particular phosphogypsum, used for the production of cement, lime and for the chemical reclamation of the soil,

There is a known method of granulating phosphogypsum by HC / Gn and pelleting of phosphogypsum in the presence of pyrite butts, and wetting is carried out with a pulp of phosphogypsum taken in an amount of 1.0-20 of the total weight of pyrite butts with a content of years s pulp 75-90% 1J .;

The disadvantage of this method is the sticking of additional raw materials (pyritic calcite) and alagi, which leads to an increase in energy consumption during the subsequent drying of phosphogypsum granules.

The closest in technical essence and the achieved result to the proposed is a method of drying and granulating pulverized phosphogypsum by heating it at 50-900 ° C with the preliminary introduction of calcium oxide and / or calcium hydroxide, cement floux, oxide and / or aluminum hydroxide into it. At the same time receive insoluble anhydrous gypsum 2J.

The disadvantage of this method is that expensive additives are introduced into phosphogypsum, which increases the cost of granulated phosphogypsum. In addition, the introduction of additional raw materials in phosphogypsum increases the energy consumption per unit of the released product.

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The purpose of the invention is to intensify the process.

The goal is achieved by the fact that according to the method of granulation

20 phosphogypsum at 50-700C granulation is carried out in the presence of carbon monoxide and / or hydrogen at a concentration of 0.05-5.0 mol. /.

The presence of reducing gases, which are structured by gas-forming MMj, ensures the appearance of low-melting eutectics at COO-ZOO C in the CaO - SiOj - FeO; 5 systems

CaO FeO SiO ,. Since phosphogypsum is an average having a composition of weight D: CaO 34,60; SOj 5.6; MgC 2.8; PfiOg-b50; fegO 0.12; F 035; slOg. IJOj contains components capable of forming low-melting eutectics in a reducing atmosphere.

at. it50-900 C, then this provides the gluing of the main mass, and hence the granulation of phosphogypsum.

In the presence of 1% carbon monoxide and 0.5 hydrogen in the atmosphere during the heating, phosphogypsum agglomerates at 650 ° C. Goanules are formed with a strength of kgf / cm and, - a bulk weight of 0,) 2 g / cm,

Process parameters are given in; the table.

Zergoaatratz

kcal / kg

product1500

Time Mr. wound.

Rrimer I, 1000 kg of phosphogypto digramdrate with total humidity} is fed to the granulator torus — in a fresh type, which is heated with natural gas. Natural gas is burned with excess air of about 98. The flue gases with temperature and containing 0, carbon monoxide and Q, 02% of hydrogen, dry and agglomerate the phosphogypsum particles. The total product (fractions mm) in an amount of 580 kg is cooled and sent to the consumer. The flue gases are directed to the chimney.

Example 2. 1000 kg phosphogypsum dihydrate with a total moisture content of 40% serves 8 drum granules, ch-sty, which is heated with coal. The burning of coal dust is carried out with an excess of air 0.85, resulting from

sixteen

12

14

B5

gas contains CO in the amount of 51 and 850C. The finished product (fractions 5-15 f.M) 3, the amount of 580 kg is cooled and sent to the consumer. Furnace gas | after the dryer, it is partially recycled in quantity, and the remaining 70/5 is burned and emitted into the atmosphere.

Example 3: 1000 kg of phosphogypsum hemihydrate, with a total humidity, are fed through a nozzle into a granulator torus dryer with a fluidized bed. The dryer is heated with water gas containing 2% CO with a temperature of 650 C. The dried and granulated phosphogypsum is cooled and sent to the consumer, and the flue gases burn down in front of the air recuperator and are released into the atmosphere,

Claims (2)

From the data presented in the table it can be seen that at a concentration. 5 CO 0.05 - 5.0: and / or H2. 0.05, 0.05%, or from an amount of 0.03-5.0, the best results of the process are observed. At concentrations of less than 0.05% or more than 5%, poor technical and economic results are observed, in particular, an increase in energy consumption per unit of product, an increase in drying time and granulation, a decrease in strength and grain size of the product. The invention of granulation of phosphogypsum at 50-700 ° C, distinguishes 3, so that, in order to intensify the process, the granulation is carried out in the presence of carbon monoxide and / or hydrogen at their concentration 0, mole D. Information sources, take into account during examination 1. USSR Author's Certificate No. 622780, cl. From 01 F, 1978. 2. Japan patent If, cl. C01F, 1972.