Impurities in Lithium Streams: How They Will Impact Your Economics

Lithium is primarily extracted from hard rock (spodumene ore) using hydrometallurgy or from salar brines using solar evaporation techniques. The main desirable products are lithium hydroxide and lithium carbonate salts. These salts are available in various grades, ranging from crude to superior. The main difference between these grades is the minimum lithium content and the maximum tolerable impurities. Impurities influence production processes, cathode quality and performance, and, most importantly, safety. Most lithium battery faults originate from the presence of impurities. This, coupled with production processes and safety aspects, puts pressure on material purity, with a focus on trace elements’ characteristics and their content. The total impurity is usually defined as the sum of impurities and contaminants. Today, there is extensive research and development activity on alternative lithium extraction processes, including the recycling of lithium-ion batteries, lithium extraction from clays, and direct lithium extraction from various types of brines (salar, geothermal, petro, and produced water). As these new sources of lithium are explored, it is crucial to understand the impurity profiles in the lithium streams, as most companies aim to produce/sell battery-grade lithium salts. Certain players may not achieve this due to a lack of technical know-how and the inability to invest in additional purification capital expenditure (capex). However, they may consider selling an intermediate product to an off-taker, which may be an established lithium company or even a centralized lithium refinery. Impurities will play a significant role in determining payables received from refineries (off-takers), as lithium streams with high impurities will receive very low payables, thereby affecting the economics of the intermediate producers.