Lithium potential in Zimbabwe’s mining industry
By Motive Mungoni
Inevitably due to its richness in terms of mineral wealth, Zimbabwe in recent times has generated international interests on two fronts: Lithium and oil & gas exploration. Even though these are two different natural resources, they have a huge potential of stimulating economic growth across all linkages in the minerals industry and beyond. As a result of the emerging electric motor vehicle industry, there is increased international demand for lithium mineral which is used for manufacturing batteries. The use of solar power plants to manufacture electricity internationally has also resulted in high demand for lithium world-wide. The remarkable advancements and/or improvements on technology in various fields has also generated a lot of interest, debate and focus on the prospecting, exploration, development and production of lithium resources in the mining industry of Zimbabwe. Figure 1 captures production figures for lithium minerals from 2005 to 2021.
The lithium industry in Zimbabwe can be considered a green field when one contemplates its beneficiation and value addition but not in terms of extraction as there is a rich history of mining lithium since the 1950s. Nevertheless, Figure 1 clearly shows an exponential increase in production between 2005 and 2010 due to the advent of the Information and Communication Technologies (ICT) era and the drive for a clean environment through generation of green energy. Even though lithium proven reserves are globally abundant to make batteries to transit to the renewable energy era, there are bottle necks on the supply chain side. This has been worsened in recent times by the Covid-19 pandemic and the conflict war between Russia, Ukraine and NATO. The demand for approximately 100 000 tonnes of lithium per year cannot be met at this juncture although the price of lithium keeps on skyrocketing with China battery-grade lithium carbonate prices reaching a new high of US$47 500 per tonne, rising by 495% from January 2021.
Since lithium is a mineral that is a critical feedstock into other sectors of the economy at both local and international levels, it is definitely a strategic mineral and a future mineral to be reckoned with. Besides battery manufacture, lithium is marketed in other numerous applications. It is used in three basic forms: ore and concentrate, metal, and manufactured chemical compounds. Ores and concentrates are consumed by the glass, ceramic, and porcelain enamel industries. Petalite, lepidolite, and amblygonite can be used without prior beneficiation, except hand-cobbing, whereas spodumene must be beneficiated by grinding and flotation, leaching and magnetic separation (Ihor Kunasz, 2006).
In metal form, lithium is the lightest solid element, having an atomic weight of 6.94 and a specific gravity of 0.534 (at 20°C). Lithium metal is used in the synthesis of butyl lithium. In non-ferrous metallurgy, the high reactivity of lithium with gases is used for scavenging oxygen and sulphur, converting them into stable com pounds. Lithium is also used in lithium aluminium and lithium magnesium alloys, where it imparts high-temperature strength, improves elasticity, and increases the tensile strength (Ihor Kunasz, 2006).
In addition to being the lightest metal, lithium is also the most electronegative metal and, therefore, is ideal for use in many battery applications as aforementioned. Lithium battery characteristics include high energy density, high operating voltage, wide operating temperature range, and long shelf life (Grady 1980). Present applications include heart pacemakers, military hardware, cameras, computer memory backup, watches, and measuring equipment in the oil-drilling industry. Future growth in this area may include use in rechargeable lithium batteries for handheld power tools and electronic and communications equipment and even as a power supply for electric vehicles and the total artificial heart.
Globally, Australia, Canada, and Zimbabwe have over the years been the main suppliers of lithium mineral concentrates for the ceramic and glass industry and other applications. During the 1950s lepidolite from Southern Rhodesia (Zimbabwe) was imported for conversion to lithium hydroxide at a Texas plant for producing the hydrogen bomb. After the depletion of the lepidolite, a spodumene zone was outlined, resulting in the production of high-grade spodumene concentrates. The distribution of lithium in igneous rocks is controlled by its size and its charge, and by the (MgO+FeO) iLi2O ratio. In the early stages of crystallization of a magma, that ratio is very large. Consequently, both magnesium and iron are removed by ferromagnesian minerals in preference to lithium, which is then concentrated in the residual magma. The result is an enrichment of lithium in silicic rocks and pegmatites (Strock 1936). Pegmatites are coarse-grained igneous rocks formed by the crystallization of post-magmatic fluids. Minerals within pegmatites can also form by metasomatism (Jahns 1955). Genetically the pegmatites are associated with neighboring intrusives. Mineralogically, granitic pegmatites contain feldspar, quartz, and mica as the main constituents and a variety of exotic elements such as lithium, beryllium, tantalum, tin, and cesium, which may or may not occur in economically significant concentrations.
Although lithium occurs in some 145 minerals, only spodumene, lepidolite, petalite, and some other minerals such as amblygonite and eucryptite have been commercial sources of lithium. Today, the principal sources of lithium ores and chemicals are spodumene and petalite. Interestingly, Zimbabwe has significant occurrences of lithium minerals deposits in almost all known existences which include: spodumene, lepidolite, petalite, amblygonite and eucryptite. Focus on eucryptite for example shows that it is a lithium aluminum silicate that is deficient in silica. It has a formula LiAlSiO4 and can contain 5.53% Li and the only large deposit of eucryptite is found in Zimbabwe (Bikita), where its occurrence with quartz suggests spodumene origin (Westenherger 1963).
Overally, the largest lithium-bearing area in Zimbabwe is the Bikita tin fields, which is about 60 km east of Masvingo. Important mineralized zones are in the A1 Hayat, Bikita, and Southern sectors. The pegmatite is about 1,700 m long, and its width varies from 30 to 70 m. It strikes north-northeast and dips from 14″ to 45″ east. The pegmatite is asymmetrically zoned and contains a variety of commercially important lithium minerals as well as beryl and pollucite. Bikita Minerals produces standard petalite, low-alkali petalite, container-glass petalite, and spodumene concentrate. Other minor lithium-bearing occurrences are found in Hwange, Harare, Mutare, Mutoko, Insiza, Matopo, and Mazowe districts (Toombs 1962). Production of lithium minerals increased from 18,064 t in 1993 to 49,883 t in 1997 (Mobbs 1998) but declined to 33,000 t in 2002 (Cockley 2002) before significant output was realized as shown in Figure 1.
In descending order of production, the world’s largest lithium chemical producers in 1999 were Chile, China, the United States, Russia, whilst Argentina. Australia, Canada, and Zimbabwe were major producers of lithium ore concentrates. The United States remains the leading consumer of lithium minerals and compounds and it also leads in the production of value-added lithium materials although China is now likely to overtake US in the next ten years. Evidently although Zimbabwe is a leading exporter of ore and concentrate lithium, it quickly needs to move to a period of industrial development where there is value addition of its concentrate coupled with sustained high production levels so as to ensure there are decreasing costs of production, increasing standard of living; rapid accumulation of wealth; expanding internal and external markets; approaching the zenith of commercial power After Hewett (1929) and Lovering (1943).