Virtuous cycle of destruction and total recycling of pure asbestos and asbestos-containing waste

Abstract

At the present time, hazardous waste management is a major problem, like the waste containing asbestos. The development of a process for eradicating all types of asbestos waste is a real challenge. In this study, several usefully analysis techniques (XRD, SEM–EDX, and TEM) have been used to determine what kind of asbestos is present in the waste (amphiboles and/or chrysotile). The chrysotile-containing wastes were treated with nitric acid solution (HNO3) leading to obtain pure silica and an acidic solution. Alkaline treatment using sodium hydroxide (NaOH) was also used in the case of waste-containing amphiboles. A basic solution of silica was then obtained. Finally a first valorization route was proposed with the precipitation of the ions dissolved in the acid solution and a second with the synthesis of a zeolite using the solid silica resulting from the acid treatment and the solution coming from the alkaline treatment of the amphiboles as sources of silicon. This paper describes the implementation of a complete process adapted to chemically dissolve each type of waste (according to their composition, density and fiber content) and to transform or recover all the by-products of the process.