The immobilization of heavy metals during drilling sludge utilization

• Drilling sludge utilization with obtaining a building material is proposed.
• The obtained gypsum concrete has a satisfactory environmental properties.
• Gypsum concrete strength is interconnected with the gypsum mixture content.
• The leaching of heavy metals depends on the gypsum concrete age and exposure time.
• The gypsum concrete with the age above 20 days is environmentally safe materials.

Drilling sludge is formed by the drilling of oil wells. This waste adversely affects the environment due to the content of heavy metals in its composition. So far, its burial was carried out in sludge pits made without walls and bottom isolation, which promotes migration of pollutants into the environment. The idea of the author is recycling of drilling sludge in building material such as gypsum concrete using phosphogypsum binder. Thus binding of heavy metals in the lattice sites of the obtained material occurs. Building material was prepared using phosphogypsum binder. The efficiency of this process is unknown.The purpose of the article is to determine the influence of the chemical composition of gypsum concrete mixture on the migration of heavy metals into the environment.The study was conducted by the experimental determination of the concentration of heavy metals in the extract at a different composition of the mixture, gypsum concrete age and exposure time. All factors have approximately equal influence. The binding of heavy metals increases when gypsum concrete age grows. The leaching of heavy metals from the gypsum concrete complies with the environmental regulations. There is a correlation between the composition of a mixture of gypsum concrete and compressive strength of gypsum concrete. The weight content of calcium oxide in the mixture, which increases the strength of gypsum concrete, was determined.

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