Process development options for electronic waste fractionation to achieve maximum material value recovery.

Revised legislation and bans on imports of waste electrical and electronic equipment (WEEE) into many Asian countries for treatment are driving the need for more efficient WEEE fractionation in Europe by expanding the capacity of treatment plants and improving the percentage recovery of materials of economic value. Data from a key stakeholder survey and consultation are combined with the results of a detailed literature survey to provide weighted matrix input into multi-criteria decision analysis calculations to carry out the following tasks: (a) assess the relative importance of 12 process options against the 6 industry-derived in-process economic potential criteria, that is, increase in product quality, increase in recycling rate, increase in process capacity, decrease in labour costs, decrease in energy costs and decrease in disposal costs; and (b) rank 25 key technologies that have been selected as being the most likely to benefit the efficient sorting of WEEE. The results indicate that the first stage in the development of any total system to achieve maximum economic recovery of materials from WEEE has to be the selection and application of appropriate fractionation process technologies to concentrate valuable components such as critical metals into the smallest possible fractions to achieve their recovery while minimising the disposal costs of low-value products.

Bioleaching of valuable and hazardous metals from dry discharged incineration slag. An approach for metal recycling and pollutant elimination.

Recycling of process wastes will be in future an essential step to meet the demands for valuable metals of a growing market. Depending on their particle sizes incineration slags are already used to recover metals but particle size fractions below 4 mm are still difficult to recycle. Therefore, different particle size fractions (mesh size 2 and 4 mm, high energy grinded) of dry discharged slags were used for bioleaching with and without the pure cultures Acidithiobacillus ferrooxidans or Leptospirillum ferrooxidans or a mixture of Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans in batch cultures.