As the world moves away from a hydrocarbon economy and towards one based on renewable energy sources like solar or wind power, it is critical that we consider how these changes will impact our environment.
Resources such as lithium are becoming more valuable in this new climate due to their ability provide storage for electricity when there's excess sunshine or winds, and countries are taking steps back before moving ahead so they can ensure environmental safety standards aren't compromised.
What is Spodumene?
Spodumene is a lithium aluminosilicate mineral originating in granitic pegmatites located across the world from Africa to North America and Australia.
Today, Australian spodumene ore represents some of the highest grades with concentrations around 4%.
What is Spodumene Mining?
Spodumene mining is the process of mining lithium, which typically uses the open-pit method of extracting spodumene ore using either hydraulic fracturing or cheaper and more environmentally hazardous explosives.
The mining and refining process of spodumene to produce lithium goes through different stages, each with their own environmental hazards:
Spodumene mining utilizes the traditional mining techniques most people think of: digging and drilling the Earth for rock. Large equipment (which produce greenhouse gasses) is needed to conduct the rock blasting and ore extraction necessary.
The extracted ore is graded and crushed to ensure a constant feed concentration for the following steps of the operation.
This conventional mining method produces the wastes that are associated with open pit mines, potentially releasing toxic chemicals into the environment.
The next step is to concentrate spodumene, known as beneficiation. In low grade operations, the ore will be ground in a ball mill and processed through a multi-stage counter-current flotation process.
Here, the gangue (commercially worthless part of the ore) is separated from the spodumene mineral, and the gangue ends up flowing into a tailings pond which is another problematic area of spodumene mining, albeit necessary.
Most modern industrial countries require that ponds be lined with materials that are high strength polymers designed to minimize mine water and waste movement into local soils or ground water, however, there is a saying that 'all ponds leak' which unfortunately rings true, resulting in a contamination of local ground water with chemical wastes.
The spodumene moves to a dryer and kiln that operate at about 1,000°C. This process converts the mineral into an easy-to-extract form using acid.
This stage in the process also has the potential to release chemicals in the environment, some of which can be attributed to the fuel quality, calciner design, and emission abatement steps.
High Temperature Leaching
Normally, the hot ore is leached with sulphuric acid at about 250°C. Approximately 60-80% of lithium can be solubilized in this step.
This stage produces the same environmental pollutants as the roasting process (see above).
The lithium is treated with lime to neutralize the excess sulphuric acid and produce gypsum. The waste from this process may end up in a tailings pond or it could be isolated by local regulators for separate ponds as required by law.
Further processing is done to remove other metal impurities such as calcium, magnesium, iron and so on.
This process typically utilizes ion exchange or solvent extraction techniques which produce waste streams containing various chemicals including salts and solvents from the solvent extractant circuit.
Each step of this process produces some sort of waste which also adds another expense to the process. Many times, businesses find financial value in releasing from the premises rather than handling it themselves.
These wastes cannot simply vanish into thin air, so they will likely end up in a tailings or wastewater pond.
Final Purification & Product Production
The purified lithium sulphate can then be converted to either lithium carbonate or hydroxide by adding soda ash. At this stage, sodium sulfate and gypsum are also produced as wastes that usually end up in a pond.
In order to meet 'battery grade' standards, more purification may be necessary. Any waste produced from these purification measures ultimately end up in waste ponds or lagoons.
Likewise, the filtration system's wastewater will also end up in a waste pond, but wastewater could also potentially be purified and recycled.
The Future of Lithium Mining Technology
Each step of the spodumene refinement process produces significant amounts of greenhouse gasses and requires and lot of energy consumption.
While this article focuses on spodumene mining in particular, but the same attention and environmental focus should be applied to the entire lithium extraction industry.
Lithium has been making huge waves in other industries, from the oil & gas industry to the transportation industry.
Even in the world of cryptocurrency (with the rise of LITH Token), lithium offers a method to completely revolutionize how businesses and people power their digital technology with heavy consideration regarding the environmental impact of lithium mining.
Connect with us and see how we can shape the future of the lithium mining industry and our future of clean energy!
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