Catalytic oxidative degradation of the azorubine dye in wastewater
T.V. Kon’kova, I.S. Belkina, A.D. Stoyanova, V.A. Kolesnikov
Section: Ecologization of industry
The production of high-quality phosphate fertilizers, in particular calcium acid phosphates, requires the use of ore
rich in phosphates (above 28 wt.% P2O5
) and containing a minimum amount of impurities, including harmful ones.
The absence of such large natural deposits leads to the need to enrich the existing phosphate ore containing an average
amount of phosphates (14–23% P2O5
) and contaminated with various impurities. Enrichment of polymineral phosphate
ores leads to the production of their concentrates and waste (sludge). Sludge is a mixture of clay impurities, iron compounds, phosphate substances contained in the original ore, as well as toxic surfactants used in its flotation enrichment.
This prevents the use of sludge as a secondary source of raw materials in any industry and its return to waste deposits.
The lack of methods for processing sludge leads to their accumulation and environmental pollution: the area of
fertile land is shrinking, pollution of nearby natural water bodies increases. The proposed integrated physicochemical
technology for processing phosphate ore dressing wastes using nitric acid is aimed at improving the environmental
situation in the regions producing phosphate raw materials and obtaining a number of valuable products important for
the national economy: glauconite sand, clay, hydrogen phosphate and calcium nitrate. The yield of sludge processing
products was experimentally established, which amounted to: 68.6% glauconite, 6.91% clay, 12.9% technical calcium
hydrogen phosphate, 18.2% technical calcium nitrate. Processing products – clay and glauconite sand are most widely
used in the construction industry, in particular, in the production of bricks and concrete. Glauconite sand and clay are used in the production of sorbents, paints and primers. Hydrophosphate and calcium nitrate are used in agriculture as
phosphorus and nitrogen fertilizers, respectively.
Keywords: phosphatic ore, slimes, the nitric-acid method of processing of a waste, glauconitic sand, clay, hydrophosphate of lime, nitrocalcite