Mining activities related to battery minerals
Mineral exploration
The purpose of mineral exploration is to find and study mineral deposits that could be exploited financially. A financially useful deposit is called an ore.
In Finland, basic geological, geochemical and geophysical data on the Finnish bedrock provided by the Geological Survey of Finland (GTK) is available for mineral exploration companies. Therefore, mineral exploration is usually started by studying this data. An attractive deposit may also be found on the basis of a layman’s sample. Mineral exploration is also steered towards certain areas in Finland by positive experiences in corresponding rock-type areas in the world or the successful and promising findings or existing mining activities in a certain area. One such area in Finland is the Central Lapland region where mineral exploration is carried out actively. Mineral exploration is also targeted at previously known deposits that may even have already been excavated. Usually, the question is that, when global market prices for metals rise to a sufficient level, interest in a deposit considered previously to be unprofitable increases again. These types of areas include the Mustavaara vanadium deposit and the Hautalampi cobalt deposit.
Certain metals can be found from specific rock environments. For example, greenstone zones are favourable for deposits of gold, cobalt, copper and nickel, whereas layered intrusions are ideal for finding chromium, platinum, palladium or vanadium. In Finland, the opportunities for finding lithium are the largest in pegmatite deposits.
Exploration involves great financial risks because effective exploration is expensive, and finding a deposit leading to a mine is very difficult and time-consuming.
During the first phases of exploration, the bedrock in the target area is investigated from exposed segments. Often, test pits are also excavated. The first samples are analysed, and further examinations are determined based on them. Further examinations usually involve soil samples and different geochemical studies. Geochemical studies serve to identify areas where the concentration of certain elements is higher, potentially meaning a mineral deposit.
Geophysical studies serve to determine the electrical, magnetic, radiometric and gravitational properties of the bedrock. Measurements can be carried out using aircraft or in the terrain. Using geophysics, the bedrock can also be studied deeper, and these studies help to identify the composition and structures of the bedrock, as well as the location of specific rock zones.
The aforementioned studies are nearly always carried out before moving on to the drilling stage.
Deep drilling is the most effective method in mineral exploration. It aims to obtain information from bedrock samples taken from deep inside the bedrock by means of diamond drilling. From these drill core samples, the mineralogy can be studied, concentrations can be analysed and, for example, the rock mechanics of the rock can be investigated. In addition, geophysical hole measurements are often conducted from drill holes. They can even be more than a kilometre in length, while they are usually approximately 100–300 metres long. Typically, each metre of drilling costs EUR 100–300.
The results of mineral exploration drilling steer further exploration plans. In the end, only a few exploration sites lead to more extensive studies. If the first results look promising, drilling will be continued. When a deposit can be modelled and found to be feasible for excavation on the basis of drilling, a prefeasibility study will be initiated, followed by a more detailed feasibility study and finally a final or bankable feasibility study. At this stage, plans are already very advanced and profitability has been found to be so certain that the funding of the project can be prepared. Mining permit applications are often prepared at the prefeasibility study stage.
Lithium and mining operations
A mining permit is the prerequisite for the establishment of a mine and the undertaking of mining operations. The mining permit applicant is most often a company registered in Finland, with mining as its line of business.
Lithium does not appear as a pure metal in nature; instead, it is always a compound.
Lithium’s raw material sources include salt water in salt lakes (salt pans), pegmatite deposits and sediment deposits. Lithium is processed into lithium carbonate or lithium hydroxide.
Salt deposits
The most important raw material sources of lithium carbonate are salt lake sediments and salt pans. These are particularly found in Chile and China. Before the actual separation process, salt water is pumped up and enriched by evaporating water, usually in large basins under the sun. Finally, the enriched solution is led to a process, in which impurities are removed and lithium is separated.
The world’s largest and purest lithium reserves can be found in the Salar de Atacama salt flats in Chile, which account for half of the world’s lithium.
Pegmatite deposits
Pegmatite deposits are another significant raw material source for lithium. These deposits are also called “hard rock lithium deposits”. In addition to lithium, tin, tantalum and niobium can be found from pegmatite deposits. The most common lithium mineral in pegmatite deposits is spodumene (lithium aluminium sulphate). Known deposits of this type are located in Australia, the USA, Canada, Ireland and Congo as well as Finland. Pegmatite deposits are excavated at open-cast mines or underground mines.
Open-cast mining is usually carried out by means of benching. In an open-cast mine, mining proceeds from the top to the bottom, one level or “bench” at a time. Different levels are connected to each other using vehicle routes, or ramps. In open-cast mines, bench height varies from 5 to 20 metres, depending on the mineral. Waste rock also needs to be removed to excavate minerals at open-cast mines. The work phases of open-cast mining are excavation (drilling, charging and blasting), crushing, material loading and transport.
In underground mines, a range of different methods and their variations can be used. The most common excavation methods used in the Nordic countries include sublevel stoping, benching, and sublevel caving.
Sedimentary lithium deposits
In sedimentary rock, lithium is found either in clay deposits or evaporites (water-soluble salt sediments). However, clay deposits have not so far been used in the production of lithium. Possibly the best-known evaporite deposit, Jadar, is located in Serbia.
Mineral treatment and processing
Mineral treatment methods include froth flotation, methods based on density differences, as well as magnetic and chemical methods.
Froth flotation has been the most common treatment method in Finland. The method based on density differences is used, for example, in the treatment of chromite in Finland. Magnetic methods have mainly been used in the treatment of iron ore.
The principle of froth flotation is to produce froth at the top of sludge using flotation chemicals and a strong air flow dispersion, to which removable, or usable, mineral particles adhere as a result of surface tension. Air bubbles can be produced either through electrolysis or by feeding air into the mixture mechanically or by using pressure.
All minerals are hydrophilic and, in froth flotation, certain mineral particles are converted to be hydrophobic by means of collector chemicals, causing them to adhere to the froth for further processing. Regulating chemicals are used to regulate the adherence of collector chemicals selectively to the surface of different minerals. An activator aims to activate the mineral surface for collector chemicals, and a deactivator to deactivate, to remove the mineral from the process. If the purpose of flotation is to remove gangue from valuable minerals, the process is called reverse flotation. After flotation, the valuable mineral material is washed and dried.
Spodumene can be treated, for example, as follows:
First, the ore is crushed. This phase may include optical sorting to remove any waste rock from the ore. The optical sorting of ore requires that the pre-crushed ore is washed or sprayed. The crushed ore is then fed for grinding. Ore grinding is usually carried out using either ball or rod mills, with balls or rods grinding the ore into pieces.
The grinding phase is followed by desliming using hydrocyclones. This is followed by pre-flotation. If required, the pre-flotation concentrate is pumped into magnetic separation to remove the process iron and magnetic minerals from the sludge. After this, the pre-flotation concentrate is pumped into repeating flotation. After the final repeating phase, the concentrate is thickened, filtered and stored for further processing.
Either lithium carbonate or lithium hydroxide can be produced from the lithium concentrate. In the production of lithium carbonate, spodumene can be treated with heat before soda leaching. Before filtering and ion exchange, bicarbonation is carried out. Finally, the lithium carbonate is crystallised.
Production and storage of battery chemicals
Production of battery chemicals
The active components of an electric battery are a cathode, anode and electrolyte. The different battery chemistries of Li-ion batteries are based on the use of different cathode materials. Graphite is commonly used as the anode, while lithium hexafluorophosphate is used as the electrolyte salt and carbonate esters are used as the electrolyte. Cathode materials include:
- LiNi0.8Co0.15Al0.05O2
- LiNi0.33Mn0.33Co0.33O2
- LiNiO2
- LiFePO4
- LiCoPO4
- LiFeO2
- LiMn2O4
- LiMnO2
- Li2Mn3NiO8
- Li4Ti5O12
In accordance with the CLP Regulation, many cathode chemicals are classified as hazardous to health. In particular, nickel and its compounds in powder form may be chemicals that are carcinogenic or suspected to be carcinogenic. Some carbonate esters are classified as flammable liquids. The production of the compounds listed above may involve typical chemical industry processes, such as the mixing of chemicals and the use of strong acids and alkalis, pressure, flammable solvents or heating processes that constitute a fire hazard.
The risks associated with the production of battery chemicals depend on the hazardous properties of the handled and stored chemicals, as well as the conditions in the production process, such as temperature and pressure. The safety of operations is ensured by identifying hazards, assessing the probability of the hazards and the severity of consequences, and determining measures that reduce risks. Companies must be able to prevent explosions and fires at the plant and recover any chemical leaks.
To prevent explosions, potentially explosive atmospheres (such as storerooms for flammable liquids) are identified, and it is ensured that equipment in such atmospheres cannot act as ignition sources.
When storing chemicals, it is ensured that dangerously reacting chemicals cannot come into contact with each other, not even during a leak. Dangerous chemicals are stored in their own designated places, and only the necessary volume of chemicals can be stored in the process area.
Chemical tanks and pipes must be sealed and withstand the impact of the chemicals they contain. Preventive and corrective maintenance ensures that tanks, pipes and other equipment remain in good condition and do not cause any leaks or other accidents.
The volume of dangerous chemicals at the plant determines whether a permit is required for operations and what the supervisory authority is. Plants with larger volumes of chemicals are supervised by the Finnish Safety and Chemicals Agency (Tukes), while smaller plants are supervised by rescue departments. However, both are subject to the same chemical safety legislation. If a plant is under the supervision of Tukes, a chemicals supervisor must be appointed and an internal rescue plan for major chemical accidents must be prepared.
More detailed information on the positioning of a battery chemical plant and on safety requirements is available on the chemical plants pages.
Battery chemicals as products
The production, imports, distribution, use and storage of battery chemicals are regulated in the national legislation and the EU chemicals regulations. The legislation governing chemicals is broad, covering a number of different sectors. The aim of chemical regulations is to reduce health and environmental risks caused by the use of chemicals.
Registration of chemicals, authorisations and restrictions on the use of chemicals
The EU’s REACH Regulation concerns the registration, evaluation, authorisation and restrictions of chemicals. The REACH Regulation imposes obligations on chemicals manufacturers, importers, producers of articles (such as batteries), downstream users and distributors. Parties must comply with the registration and authorisation requirements concerning chemicals, as well as any prohibitions and limitations on the use of chemicals when products are made available on the market, i.e. sold or supplied otherwise.
