Записки Горного института (Jul 2024)
Preparation and use of complex titanium-containing coagulant from quartz-leucoxene concentrate
Abstract
The search for the new high-efficiency reagents for wastewater treatment is a challenging and urgent task. Titanium-containing coagulants represent a new trend in water treatment and have a much higher efficiency that the traditional aluminium and iron-containing coagulants. The high cost of reagents significantly hinders their implementation. Complex titanium-containing reagents are coagulants prepared by modifying the traditional coagulants by adding 2.5-10.0 wt.% titanium compounds. In this work, titanium tetrachloride prepared from quartz-leucoxene concentrate was prehydrolyzed with subsequent double decomposition with sulfuric acid. The resulting mixture of hydrochloric and sulfuric acids was neutralized with aluminium hydroxide/oxide to form a self-hardening mixture (chemical dehydration). The sample of a complex sulfate-chloride titanium-containing coagulant was a mixture of AlCl3·6H2O – 5-20 wt.%, Al2(SO4)3·18H2O – 70-90 wt.% and TiOSO4 – 2.5-10.0 wt.%. It was proved that by changing the ratio of aluminium oxide/hydroxide and titanium tetrachloride at the stage of prehydrolysis and double decomposition, it is possible to obtain samples of a complex coagulant with different contents of the modifying additive of titanium compounds. An assessment of the coagulation properties of the complex reagent demonstrated its higher efficiency in cold water compared to aluminium sulfate. Studies on the use of the complex titanium-containing coagulant in the process of wastewater treatment from phosphate anions and suspended matter demonstrated its higher efficiency as compared to that of traditional reagents. The advantages of the prepared reagent are a reduction in the effective dose of the reagent, minimization of residual concentrations of pollutants in purified water, intensification of the processes of sedimentation and filtration of coagulation sludge. Purified water can be reused in the recycling water supply system. The use of quartz-leucoxene concentrate and titanium tetrachloride obtained from it as the source material would not only minimize the cost of the resulting complex coagulant, but also take a step towards the implementation of the Zero Waste concept.
