Mineral Beneficiation

Coal to liquids (XTL)

Botswana has substantial coal deposits, one of the largest untapped potential resources in the world at over 212 billion tonnes, that comprise of 3.3–5 billion tonnes of actual recoverable reserves, of which 40 million tonnes are proven reserves. The coal beneficiation project objective is towards transformation of coal into higher value commercial products such as liquid fuels and petrochemicals for the local market in Botswana and as well as for international markets. BITRI has a state-of-the-art gasification pilot plant that is bedrock of the XTL products (petrochemicals and liquid fuels) from the produced synthesis gas (syngas = CO + H₂). It is envisaged that with the abundant coal reserves Botswana has, they can be harnessed to achieve energy independence and diversify the economy.

Carbon Materials from Botswana Coal

There is a global demand of carbon materials for a plethora of industrial applications. As such coal is one of the major sources of carbon. BITRI is developing processing technologies on synthesis or production of high-value carbon materials (such as graphite, graphene, graphene oxide and carbon nanotubes from coal). The carbon materials can be used as starting materials/substrates in different industries for instance graphite is used as the anode in Li-ion batteries for EV industry and battery industry (Li ion battery industry) as well in electronics industry as a supercapacitors.

Clean Coal Technologies

The environmental concerns on the use of coal cannot be taken lightly. Thus, we see developing technologies that would either convert emissions from coal into benign but useful products or capture and storage of emissions for further processing to be critical in adding value to coal. It is critical to note that Botswana’s coal can hold/store methane in the so-called “coal bed-methane” deposits. It is in the light of this characteristic of Botswana coal and literature precedence that we embarked on the use of Botswana’s coal as adsorbent for carbon dioxide i.e. carbon sequestration. We have developed a method that uses green solvents that is subcritical and supercritical water, supercritical CO₂ and ethanol or as blends/mixtures in cleaning coal to reduce or minimize adverse effects of NOx, SOx emissions by reduction or extraction of sulfur, nitrogen species in the coal. We have also explored the use of pressurised hot water extract (PHWE) and the results are promising in reduction of mineral content in the coal.

Coal Fly Ash Beneficiation

Coal fly ash has been proposed as a potential source to supplement rare earth elements (REEs) mining. However, there is a lack of comprehensive research of the typical REEs contents in coal fly ash, particularly in Botswana. The extraction, separation, and comparison of REEs among the major types of coal feedstocks that determine fly ash composition remain largely unexplored. Thus, the growing global demand for rare earth elements (REEs) and the need for sustainable and economically viable sources of REEs. REEs are essential components in various high-tech industries, including renewable energy, electronics, and defense. However, the current supply of REEs is primarily dominated by a few countries, leading to potential supply chain disruptions and geopolitical risks. We are currently developing extraction and separation protocols for REEs in coals and coal fly ash of Botswana to address the critical need for a sustainable and diversified supply of REEs.

Base metals

The other mineral resource Botswana has in abundance is base metals, predominantly copper and nickel ore deposits in North-Eastern Botswana. The ore deposits are mainly nickel-copper sulfide deposits. Recently, the Kalahari Copper Belt in North-Western Botswana is emerging as a remarkable “hotbed” of copper, copper-silver and platinum-group minerals mining jurisdiction. BITRI established the base metal beneficiation project to work with the mining industry to fully exploit base metals ores, tailings, concentrate and matte for beneficiation in Botswana. The project’s aim is to explore and adopt, and/or develop innovative environmentally friendly “green” technologies in the extraction of base metals especially copper and nickel from slag, tailings, concentrate and low grade ores. Base metals are used to make high-end materials used in construction, automobiles, petrochemicals, fabrication and welding, power and renewable energy, electronics, transportation and water sectors. Nickel and copper use in the lithium-ion battery sector is growing rapidly especially for the electric vehicle (EV) industry.

Platinum group metals (PGMs)

There is no well-established PGM mining and processing industry in Botswana. Notwithstanding/Despite, the advent of new and old mineral discoveries/explorations highlight that some of the base metal ores have PGMs. For instance, the commercial viability to process the BCL matte and slag for PGMs has never been fully explored or exploited. PGMs are a group of six elements, namely iridium (Ir), osmium (Os), platinum (Pt), palladium (Pd), rhodium (Rh) and ruthenium (Ru). PGMs together with gold (Au) and silver (Ag) are classified as noble or precious metals because of their high corrosion and oxidation resistance. Geologically, PGMs associate with base metal sulfides such as chalcopyrite (CuFeS₂), millerite (NiS), pentlandite (Fe,Ni)₉S₈, pyrite (FeS₂) and pyrrhotite (Fe₁−xS). Gangue minerals associated with PGM-containing minerals are feldspar, biotite, plagioclase and pyroxene. Interestingly, the ores from BCL and Tati Nickel Mining Co. are sulfide ores. As such, PGMs are or can be considered to be important byproducts of copper and/or nickel production. PGMs have a number of industrial processes and commercial applications such as in automotive industry, emission control for vehicles, hydrogen fuel cells, jewelry, electronics, dentistry, catalysts, biomedical components, temperature measurements, special crucibles and investments amongst others. BITRI is developing “green” hydrometallurgical processes for extraction of nickel, copper, and PGMs from low-grade ores, tailings, and slag, that aligns with the growing demand for sustainable mining practices.

Catalysis is the foundation of many of our research projects. Thus, it was imperative to establish a catalysis programme and apply it on projects that we are working on and those we intend to work on in future. Most of our projects have synergy with catalysis. We have developed a catalysts for conversion of syngas (CO + H₂) and direct CO₂ hydrogenation to methanol (MeOH) and dimethyl ether (DME). We have developed catalysts from coal fly ash as substrate to be used in array of applications such as wastewater treatment and synthesis of biodiesel from waste cooking oil.