Monthly Archives: February 2017

Impacts of mine waste on post-mining land use

More from the Minerals to Metals Symposium 2016

Impacts of mine waste on post-mining land use – a case (study) of Luanshya town, Zambia
Mining and mineral extraction in Zambia has had long lasting and transformative effects on the country’s economy and landscape. Since the first commercial copper production in 1928 in Luanshya, a town located 337km north of the capital Lusaka, its landscapes have been drastically altered. To determine the extent of this alteration, spatial land use data will be collected and used to generate maps.

Furthermore, map-based interviews will be held with some local stakeholders in the town to document the diversity of their memories, experiences and perceptions about mining in the town. Analyses of these data will help demonstrate how the physical and socio-economic transformations associated with industrial development have shaped land use in this mining town. Past works on the Copperbelt have concentrated on the types and extent of pollution in the concerned mining towns.

This study employs a livelihoods approach to assess the current situation in Luanshya, as well as examines the effects of land changes that have been caused by mining activities. The study will also determine how these mining activities have affected the environment and land use patterns. This work is important because mine waste is a sustainability challenge that needs to be addressed. The study will conclude by exploring land use opportunities that can help improve the environmental sustainability of this once mining-dependent town.
Sakuwaha Grace Kabang’u
MPhil in Sustainable Mineral Development
“Kabang’u is a geoscientist working for Rio Tinto Zambia in mineral exploration. When she is not camping in the bush searching for the next copper mine, she spends time studying, reading novels, or learning dance. Growing up in a big family taught her that there is no substitute for hard work.”

Rehabilitated Opencast Mines in the Witbank and Highveld Coalfields
Coal is still South Africa’s primary source of energy. South Africa is ranked seventh in global coal production and is the sixth largest coal exporter. The extraction of coal, whether through underground or opencast mining, is often associated with serious environmental implications. Opencast mining is particularly of a destructive nature and compromises highly potential agricultural lands, ecologically sensitive environments and development in surrounding areas.

The Witbank and Highveld coalfields lie within the critically endangered grassland biome. Approximately 46% of South Africa’s total high potential arable soils are found in Mpumalanga. About 12% of these soils have been altered by coal mining activities; with a further 14% subject to coal prospecting applications. Post-mining land rehabilitation and the understanding of the process is therefore vital in order to ensure that land destroyed by mining is put to sustainable use such as agricultural or grazing purposes.

The purpose of the research project is to investigate the prospects of sustainably using previously poorly rehabilitated opencast mined areas in the Emalahleni and Middelburg areas. The aim is to review the level of the initial rehabilitation carried out, particularly looking at the soils. As well as establish the potential and benefits of using the land.
Nontobeko Gule
MPhil in Sustainable Mineral Development
“I’ve learned that no matter what happens, or how bad it seems today, life does go on. I’ve learned that I still have a lot to learn. I’ve learned that people will forget what you said, people will forget what you did, but people will never forget how you made them feel.”- Maya Angelou

 

Minerals To Metals Symposium 2016

Mine waste

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

Fabricated soils from ultrafine coal waste

More from the Minerals to Metals Symposium 2016

Fabricated soils from ultrafine coal waste
The use of fabricated soils from processing coal waste in mine reclamation projects is an innovative part of the solution for a more sustainable coal mining production. It enables the reduction of the direct environmental, social and economic impact related to current (end-of-pipe) waste disposal approaches and rehabilitation of mine sites.
Trough separation of the acid-generating sulphide fraction as well as further coal production from the fine coal waste using two-stage flotation or an equivalent separation process, a largely benign waste fraction results.
The re-purposing of this waste particulate material into a fabricated soil will be investigated through the addition of amendments such as algae, anaerobic digested sludge and organic compost.
The chemical, physical and biological aspects of the fabricated soil will be defined, including its drainage, nutrient profile and absence of toxic components. Its potential use in mine-site rehabilitation also will be considered.

Juarez Amaral Filho
Postdoctoral Fellow
“Se os senhores da guerra
Mateassem ao pé do fogo
Deixando o ódio pra trás,
Antes de lavar a erva
O mundo estaria em paz!”
Chimarrão, nectar of life and peace by João Chagas Leite

Recycling and utilization of mine waste: A gold case study
The discovery of world-class gold deposits in the late 19th century led to the transformation of South Africa’s economy from an agricultural to a modern industrial economy. Despite its significant contribution to the economy, the mining industry has been plagued by labour disputes and is widely criticized for its negative environmental impacts. Of particular concern is that fact that the beneficiation of gold results in the production of large quantities of solid waste (including overburden, waste rock and tailings), which accounts for approximately 42% of all waste generated in South Africa.

This waste material is typically discarded in tailing deposits, which cover approximately 400km2 in surface area. These tailings dam pose a significant environmental risk as they can lead to the formation of acid rock drainage (ARD) generation, water pollution, soil contamination, flooding resulting from burst tailings dams and respiratory health impacts to surrounding communities.

To minimize the impacts of conventional disposal on the environment date, three main approaches to mineral waste management have been adopted in South Africa. These are namely rehabilitation, recovery, and reuse. While these approaches have been implemented, the reuse option still remains constrained in South Africa. The research findings suggest that the reuse of mine waste is influenced by different parameters such as technology, legislation, material suitability and economics. These parameters can either facilitate or hinder the reuse of mine waste.
Lesley Sibanda
MPhil in Sustainable Mineral Development
“You only live once, but if you do it right, once is enough.” – Mae West

 

Minerals To Metals Symposium 2016

Fabricated soils

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

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.

Kinetics of lime dissolution in neutralisation of acid mine drainage

More from the Minerals to Metals Symposium 2016

Kinetics of lime dissolution in neutralisation of acid mine drainage
Acid mine drainage (AMD) contains high concentrations of dissolved heavy metals and sulphates, with pH values as low as 2.5. This can be toxic to plant and aquatic life, it is thefore important to treat acidic effluents before being discharged to the environment. AMD treatment involves neutralisation process, where AMD is reacted with alkaline solution to adjust pH to acceptable environmental standards. During neutralisation process, iron and other metals are removed or recovered in a form of oxides or oxyhydroxide precipitates.
Lime is a prefered neutralising agent because of it’s reactivity and accessibility. Beside lime’s potential benefits, it’s neutralisation fuction is reported as a very complicated task especially when high efficiency is targeted. This study therefore seeks to establish a rigorous analysis on lime dissolution kinetics in the context of South African AMD neutralisation. This is to be achieved through emperical models or established mathematical based models, labolatory studies such as the effect of dissolution of lime in a stirred tank under different conditions such as temperature, pH and concentration of different cations are to be explored.

This will then provide more value for the successive studies on the formation of iron precipitates and other metal recovery during lime neutralisation.
Senzo Mgabhi
MSc Chemical Engineering
“Other than deeper interest in water treatment, hydrometallurgy and chemical engineering science, Senzo is passionate about environment, nature conservation and sustainable development. As a Chemical Engineer, with attained analytical skills and growing aptitude in critical thinking, he seeks to pitch the sustainable solutions that are ethical, safe and environmental friendly.”

Two stage separation process for the management of sulfide wastes and associated ARD risks
The beneficiation of coal for down-stream use generates large quantities of solid waste, including overburden, discard and ultra-fine tailings. These wastes contain sulfide minerals, particularly pyrite, which oxidize and give rise to acid rock drainage (ARD), a major source of ground and surface water pollution.

Current attempts are focused on end-of-pipe technologies such as carbon capture and storage, clean coal combustion technologies, mining operations and control of pollution. Very little emphasis has been placed on opportunities related to use or recycling of downstream wastes. Sustainability through resource conservation and recycling is a growing field of research and development in which recent researchers have demonstrated the benefits of the principles of sustainability in contrast to the current end-of-pipe approaches.

Previous studies at the University of Cape Town in South Africa have demonstrated the technical feasibility of using froth flotation for separating pyritic sulphur from coal ultrafines in a two-stage process, which is aimed at simultaneously eliminating ARD risks and recovering valuable coal. In all case studies investigated to date, desulfurization flotation of base metal sulfide and coal processing wastes resulted in a sulfide-lean tailings which is non-acid generating thus effectively eliminating long-term ARD risks.

Juarez Amaral Filho
Postdoctoral Fellow
“Environmental engineer with PhD in Mineral and Environmental Technology at UFRGS – Brazil. Currently researching under the supervision of Prof. Harrison and Prof. Broadhurst, as a post-doctoral fellow. His research interests are environmental issues related to characterization, processing, discard and disposal of minerals wastes and effluents; mineral waste recycling and water reuse; and, ARD prediction, minimization and mitigation.”

UCT urban mine-understanding the local context to e-waste processing
Printed circuit boards (PCB’s) from end of life electronic waste (e-waste) contain significant quantities of metals. Some of these can be recovered profitably (extracting positive value) while others can become a hazard to the environment and humans if not disposed of appropriately (reducing negative value). High grade PCB’s are attractive to e-waste exporters, who because of the nature of the local industry, have the option to cherry pick these leaving behind low grade PCB’s with a low positive value or even negative value.

There is a need to develop and test process flow sheets that lead to optimal extraction of positive value and the responsible disposal of benign waste streams in the treatment of low and mixed grade PCB’s. The process flow sheets must be suitable for adaptation by emerging economies where energy costs, and availability of infrastructure, as would be required for a blast furnace operation, are a primary consideration.

A multi-stage hydrometallurgical treatment process, in which whole and cut up unpopulated PCB’s are processed is to be developed and tested. In this proposed process, low grade PCB’s (usually not multi-layered) go into sequential chemical baths, dissolving different groups of metals at each stage. The remaining substrate can then be sent out for further recycling. Economic and feasibility studies of the processes flow sheets at small to medium scale plants will be investigated.
Thandazile Moyo
Postdoctoral Fellow
“To laugh often and love much; to win the respect of intelligent persons and the affection of children; to earn the approbation of honest citizens and endure the betrayal of false friends; to know even one life has breathed easier because you have lived—this is to have succeeded.”- Ralph Waldo Emerson

 

Minerals To Metals Symposium 2016

Acid mine drainage

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