апрель 2019

Creating coagulants from red mud as a way of the circular economy

S. Kyrii , I. Kosogina , D. Nechyporuk
Химия и современные технологии
Abstract / Full Text

The issue of accumulated waste utilization in large quantities becomes more and more acute every year. More and more urgent are circular economy technologies or resource-saving technologies that could reduce the accumulated amount of industrial waste and make cheaper the process of obtaining the finished product. It is possible to implement effective circular economy technology, for example, using wasters red mud produced from alumina production. The total amount of red mud produced in the world fluctuates from 60 to 120 million tons. Therefore, for the problem of rational use and recycling of red mud deservedly paid great attention.

It has been established that red mud can be used in various industries, for example in ferrous metallurgy, for the production of pig iron, alumina and various separate components, the building industry for making bricks and cement, ceramic, glass, etc. Due to the high content of iron oxides (up to 55%) and aluminum (up to 30%), red mud can be used in water purification technology as coagulants or adsorbents after their synthesis processes.

The purpose of this work is to synthesize and test the using effectiveness of coagulation reagents based on red mud obtained in the technology of wastewater treatment from compounds of organic origin.

The liquid coagulation reagent (LC) was obtained by acid activation of red mud (mass ratio of hydrochloric acid to red mud 1:1, synthesis duration 60 min, temperature 100 °C). The verification of the reagent efficiency was checked on model waters contaminated with natural organic matter (NOM) using Jar-test and compared with widely used coagulant Al2(SO4)3 (Fig. 1).

Figure 1 − Effectiveness of color removal by coagulants

As can be seen from the figure, the obtained reagent from wastes of alumina production shows a high color removal (from 62 to 13 degree), is competitive compared with Al2(SO4)3. It makes it promising for use in the circular economy because two problems are solved at once: recycling of waste and creation of a new effective reagent for wastewater treatment.