Development of a process flow sheet for selective metal recovery

More from the Minerals to Metals Symposium 2016

Development of a process flow sheet for selective metal recovery from waste printed circuit boards and its evaluation using a techno-environmental and socio-economic framework
Waste printed circuit boards (PCBs) from end-of-use Waste Electrical and Electronic Equipment (WEEE) contain significant quantities of metals. Some of these metals are of economic value while others are hazardous to the environment and humans if not disposed of appropriately. An industry has emerged globally for the collection, dismantling and separation of high value components from WEEE. The South African WEEE industry comprises of collection, dismantling and initial separation of components, however, the high value fraction is exported to these centralised operations in Europe, thus leaving the low value fraction and potentially hazardous residue behind.

This project aims to develop and evaluate hydrometallurgical process flow sheet options that lead to optimal recovery of value and hazardous metals along with minimisation and sustainable management of waste streams in the treatment of PCBs. The process design will be evaluated within a cluster of small-to-medium-scale industries that contain collection, dismantling and separation units to provide the feed. The evaluation will be based on both, a techno-economic comparison to the established centralised, commercial-scale processing of PCBs, and a socio-economic evaluation of such an industry cluster in terms of job opportunities, skills development and the existing legal and regulatory framework.
Zaynab Sadan
MSc Chemical Engineering
“No man can reveal to you aught but that which already lies half asleep in the dawning of your knowledge. The teacher who walks in the shadow of the temple, among his followers, gives not of his wisdom but rather of his faith and his lovingness. If he is indeed wise he does not bid you enter the house of his wisdom, but rather leads you to the threshold of your own mind.” – Kahlil Gibran

Potential Value Recovery from Waste Tyres via Aqueous Phase Reforming
Human population growth and the industrial era has brought about an increase in waste generation. Recycling of waste is becoming increasingly important due to the emphasis placed on environmental sustainability of our planet. Polymeric waste, particularly tyres, are difficult to dispose of and the stockpiles attract mosquitoes, vermin and dangerous reptiles, and is a fire hazard. Burning tyres release hazardous pollutants, are difficult to extinguish and expensive to clean- up. The bulky nature of tyres does not allow for it to be compressed or folded, creating space problems at landfill sites. To mitigate these challenges, waste tyres has the potential to be used as a resource if further recovery of value can be extracted.

Tyres are composed of a mixture of synthetic and natural rubber and other compounds, which together form a highly complex structure. The complexity derives from the three dimensional network, formed between polymers, sulphur and a variety of other compounds created via the irreversible vulcanization reaction.

This reaction creates transverse bonds that connect the polymer chains to form the cross-linked structure of rubber which result in a product that is elastic, insoluble and which cannot be reprocessed. Current technologies for fuel recovery from waste tyres are energy intensive. An alternative method of Aqueous Phase Reforming (APR), a low energy cost method that uses water as reaction medium, on amphiphilic tyre particles are proposed.

Alvira Mentoor
PhD Chemical Engineering
“Dreams are messages God sends us about the future
Dreams light up my path and allow me to see clearly what lies ahead
Dreams calm my soul, lift my spirit and strengthen my bond with God
Without dreams I am a lost soul”

Introducing Loop-closure for Phosphates into a Provincial Development Strategy: An analysis of Overlaps of Primary and Secondary Phosphate Processing Technologies
Almost 90% of the global phosphoric acid demand is primarily attributed to fertiliser production for use in the agricultural industry. South Africa primarily relies on the processing of limited igneous phosphate ore deposits found in Phalaborwa, Limpopo for the supply of phosphates; but this is not sustainable as the worldwide phosphate ore reserves are expected to last approximately 100 years (Smil, 2000) due to rising demands and declining ore grades.

The work proposed work herein investigates the following:

(i) The possibility of using source-separated human urine (or its derivatives) as a raw material at an existing phosphate processing plant,

(ii) the socio-economic impacts of operating a small business enterprise that would be involved in the supply of ‘raw’ or pre-treated urine.

To fulfil the abovementioned aim

(i), flowsheet analyses, including process simulations on ASPEN Plus will be done to study common phosphoric acid production processes. Urine, and its derivatives will be added at several selected stages of the chemical process and the effects on costs, product flow & yield, resource intensity and eco-efficiency monitored. The second aim of this research will be fulfilled by predicting and assessing the success of a business enterprise such as this through comparison with the already operational REDISA model for waste tyres.
Sizwe Vidima
MPhil in Sustainable Mineral Development
“Sizwe Vidima was born in a small township called Clermont, located on the west of Durban and moved to Cape Town for tertiary studies in Chemical engineering. Sizwe is currently a candidate in the Minerals to Metals programme: MPhil in Sustainable Mineral Resource Development and is passionate about inclusive economic development. Words Sizwe lives by: Carpe Diem.”



Minerals To Metals Symposium 2016

Selective metal recovery

Dust Monitoring Equipment – providing equipment, services and training in dust fallout management to the mining industry.

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