LT6605B - Eco - friendly mineral filler - Google Patents

Abstract

The invention can be used in the industry of technical rubber articles, artificial leather, paints, polymer articles, building mixes and other articles. The method of processing phosphogypsum into organic mineral filler includes grinding of phosphogypsum, lime neutralization, combustion at 500-550 oC to constant weight per unit weight.

Description

Description of the invention

The invention can be used in the industry of technical rubber products, artificial leather, paints, polymer products, construction mixtures and other products.

Phosphogypsum, which consists mainly of calcium sulphate dihydrate with a low phosphate content, is formed during the production of phosphoric acid by the treatment of apatite with sulfuric acid. Recently, AB Lifosa phosphogypsum has accumulated within 45 min. tons, the waste mountains cover about 84 ha, the height of some waste mountains reaches 60 m. and more. These production wastes pollute the environment and groundwater, so their processing into technical products is promising.

There is a known way to make mineral fillers from phosphogypsum that would replace natural chalk, thus reducing production costs, technical rubber products, artificial leather, paints, polymer products, construction putties, and so on. industry (Patent No. 4440 of March 30, 1998). Phosphogypsum from the landfill is excavated with a shovel excavator, loaded onto dump trucks or railway platforms and transported to a workshop for processing into mineral aggregates. To separate coarse mineral impurities, phosphogypsum is passed through a vibrating sieve. The sieved phosphogypsum is fed to a sludge pool, where the phosphogypsum is whipped with water. The pulp from the sludge pool is pumped to a reactor containing a pre-prepared lime slurry. The phosphogypsum pulp is fed to the reactor until the pH of the pulp drops to 7.5-8.5. The pulp neutralization process is controlled by an automatic pH meter, measuring and recording the pulp pH curves. The neutralized phosphogypsum pulp is pumped to a ball mill, where the required fineness of grinding the phosphogypsum, depending on the use of mineral aggregates, can be achieved. The appropriately ground phosphogypsum pulp is pumped to a vacuum filter and the filtered mass is burned in a rotary kiln.

We offer to produce ecological mineral filler from phosphogypsum, which would replace natural chalk in technical rubber products, artificial leather, paints, polymer products, construction mixtures, etc. industry, according to the following technological scheme:

Phosphogypsum waste landfill

Excavation

transporting

Coarse sieving

Flushing with water

Sedimentation

Neutralization

Milling

Vacuum filtration

Combustion

Cooling

Pronunciation

Storage

Phosphogypsum is excavated at a landfill with a single-bucket excavator, loaded onto dump trucks or railway platforms and transported to a workshop for processing into mineral aggregates. Phosphogypsum is sieved through a vibrating sieve to remove large mechanical impurities. The sieved phosphogypsum is fed into a sludge pool where it is whipped with water.

Larger mechanical impurities, which were not separated by coarse sieving during coarse sieving, settle to the bottom of the sludge pool, so the slam pool is periodically cleaned of mineral impurities.

The pulp is pumped from the sludge pool to the sand settlers. Depending on the size of the sand particles to be deposited, the pulp remains in the sand settler for a few to several hours.

The pulp from the sand settlers is pumped to a reactor containing a pre-prepared slurry of lime. Lime extinguishing time 10-30 min. The rate of pH decrease of the lime suspension is maintained as follows: in the pH range 12.8-12.0 not more than 0.16 pH units / min, in the pH range 12.0-6.5 not more than 0.6 pH units / min. The phosphogypsum pulp is fed to the reactor until the pH of the pulp drops to 7.0-7.5. This pulp is kept in the reactor for 10 minutes. The neutralization process is controlled by an automatic pH meter, measuring and recording the pH curves of the pulp.

The neutralized phosphogypsum pulp is pumped to a ball mill, where, depending on the grinding time, the required degree of grinding of the phosphogypsum can be achieved, depending on the use of mineral aggregates.

The ground phosphogypsum pulp is pumped to a vacuum filter, which filters up to 15-20% of the residual moisture. The filtrate is pumped back for lime slurry production.

The filtered phosphogypsum mass is burned in a rotary kiln at a temperature of 500-550 ° C to a constant unit weight.

The calcined phosphogypsum is cooled to a temperature of 40-50 ° C, packed in 25.0 kg paper bags with an inner polyethylene layer, stacked on pallets and stored in a closed warehouse.

Claims (1)

DEFINITION OF THE INVENTION Process for processing phosphogypsum into an organic mineral filler comprising whipping the phosphogypsum with water, precipitation, milling, vacuum filtration, combustion, characterized in that the phosphogypsum is burned at a temperature of 500-550 ° C to a constant volume per unit weight to obtain an organic mineral filler.