The Intergovernmental Panel on Climate Change (IPCC) has indicated that limiting the global temperature rise to just 1.5°C will require rapid, far-reaching, and unprecedented changes in all aspects of society. According to model projections from IPCC’s Special Report: Global Warming of 1.5°C, global anthropogenic (human-caused) CO2 emissions need to fall by 45 percent by 2030 and reach net-zero by 2050.
The path to net-zero carbon emissions is a global, multi-sector challenge and developing road maps to achieving that goal requires industry commitment, innovation, and new technological solutions. The challenges to achieving decarbonization road maps in the mining industry need to be tailored by operation, addressing the key pillars of decarbonization: energy efficiency, hybrid power, microgrid integration, alternative vehicles, mine design, and process adaptation to alternative energy sources. Specifically, one of the critical challenges that needs to be addressed is the reliance on diesel fuel.
The mining fleet is one of the industry’s primary sources of on-site greenhouse gas (GHG) emissions. Mobile mining equipment at a surface mine can account for up to 30 percent of on-site GHG emissions—or up to 80 percent if the mine doesn’t have contiguous smelting or refinery facilities. Large mining haul trucks can represent more than 50 percent of the total surface mobile fleet’s GHG emissions.
Mine exploration, construction, drilling and maintenance result in land-use change which could lead to deforestation, soil erosion, the contamination of soil and water profiles and increased noise levels. Mining pollutes underground and surface water systems and create native impacts downstream.
Water is essential to mining, as it is used in several activities, including mineral processing, dust suppression and employee use. Mining can affect both the availability and the quality of water in surrounding environments, which requires careful planning and mitigation actions to minimize these impacts. Responsible water management includes the protection of water quality downstream of our operations, improving water use efficiency, and engaging with communities of interest on watershed management.
Mining and mineral processing can also impact air quality through particulate and gaseous emissions from activities like drilling, blasting, crushing, collection and storage, and transportation along the value chain. Managing these emissions allows companies to limit their potential air impacts while benefiting from operational efficiencies and cost reduction.
The CO2 emissions might be in a range of 40 to 50 percent from diesel that used in equipment plus another 30 to 35 percent from nonrenewable electricity. Impacting green house emission(GHG) on the environmental is undeniable. Three emission’s sources are electricity generation, diesel, and supply chain and transport. Net Zero Emission in the mining industry can be future target as other industries (ex. Building, transportation).
microgrids have become one of the main solutions in mining environments to help drive energy-efficient outcomes. The power distribution grid during periods of heavy demand can use as an emergency power back up. By using microgrids, different sources of energy such as electric or solar could design.
Short Term GHG reduction:
Consume renewable energy to reduce GHG emmissions
Long Term GHG reduction:
BEV pathway: Move to a fully electric mobile equipment fleet, with haulage trucks charged on pantograph and others charged using a battery-swap approach.
Hydrogen pathway: Use an FCEV mobile fleet, combined with a buildup of green hydrogen capacity derived from wind or solar.
Synthetic fuel pathway: Keep existing equipment, but use drop-in synthetic fuels created from green hydrogen and carbon capture, utilization, and storage.
Potential Sources of Contamination in Wastewater:
The primary environmental concerns associated with ore extraction activities are the disposal of waste rock and the release of mine used water. Another environmental impacts are dust, noise and vibration because of drilling, blasting, and transportation activities. Acidic drainage, alkaline effluents, metal leaching, cyanide, ammonia, suspended solids are some source of contamination.
Acidic Drainage: Sulphide minerals are ore minerals for many base metals, such as copper, lead and zinc, and are ubiquitous in ore deposits. Sulphides may also occur in host rock for ore deposits, and as a result they are common in waste rock. Sulphides are important from an environmental perspective because, in the presence of water and oxygen, they can oxidize to create sulphuric acid, a process commonly known as acidic drainage and also known as acid mine drainage or acid rock drainage. The result is the generation of metal-laden effluents of low pH. Acidic drainage can have very significant impacts on aquatic ecosystems unless it is carefully managed, and it can lead to long-term liability and effluent treatment costs for the mine owner/operator.
Alkaline Effluents: Many ore separation processes, particularly flotation separation, are most efficient at an alkaline pH, and chemical additives are used to ensure an alkaline pH, sometimes as high as 10 or 11, during processing. As a result, effluents from ore processing facilities are frequently alkaline, even at the point of final effluent discharge. At some sites, pH adjustment is required to lower the effluent pH prior to discharge.
Metal Leaching: Wastewater from mining and ore processing facilities can contain metals that naturally occur in the rock. Most metals are more soluble in water at low pH, so the concentrations of metals are frequently elevated in acidic drainage. However, metal leaching can also occur in cases where acidic drainage is not a concern.
Cyanide: Cyanide is used in the recovery of gold in many facilities that process gold ore. Some cyanide is reused in processing but some is discarded in tailings. As a result, wastewater from facilities using cyanide mills may contain cyanide and a number of cyanide compounds.
Cyanide is also used in small amounts in some flotation separation circuits. Thus, cyanide compounds may also occur in wastewater from tailings from some base metal flotation mills.
Ammonia: Ammonia may be present in wastewater from mining operations as a result of the use of ammonium nitrate and fuel oil (ANFO) as a blasting agent. Any ammonium nitrate spilled in preparation for blasting or left over after a blast may contribute to increased ammonia concentrations in wastewater. In addition, ammonia may occur as a decomposition product from cyanide wastes.
Suspended Solids: Wastewater may contain suspended solids ranging from colloidal (non-settleable) to settleable materials. The discharge of effluents with high levels of suspended solids can cause a range of problems in aquatic environments that include impeded oxygen intake by fish and reduced light availability for aquatic plants. Depending on the composition of the solids in suspension, the settling of these sediments can also result in the contamination of sediments, particularly with metals.
Waste Rock and Tailings Disposal management:
The production of both waste rock and tailings continues throughout the mine operations phase, and effluents originate from both. Effluent from waste rock is often sent to the tailings disposal area for treatment prior to final discharge, but it may also be directed to a separate treatment facility. The release of contaminants control is the crucial mine waste management.
Groundwater seepage is another concern for both waste rock piles and tailings management facilities; seepage into the groundwater could result in the release of contaminants through a permeable foundation layer or other instability.
The risk of metal leaching and acidic drainage have to consider in the design of waste rock piles and tailings management facilities. Several methods can use to prevent the leaching. The most effective method is subaqueous disposal. Also, phytoremediation might be consider as well in some cases.
Disposing waste rock or tailing under water can decrease the exposure of the material to oxygen . Reducing the risk of acidic drainage and metal leaching problem are the result of oxidation reactions avoidance .
Another method that can be used including:
- Dry covers consisting of alternating layers of material of different porosity to limit water infiltration;
- Dry covers using innovative materials such as sewage sludge stabilized by lime or sludge from pulp and paper mills. Acidic drainage from mines is commonly treated with lime. A by-product of this treatment is sludge. The composition of sludge varies, and sludge may contain a wide range of metals. The volumes of sludge produced are large, and in some cases they may exceed the volume of tailings produced over the life of an operation. Sludge is generally disposed of on site, but it may also be sent to smelters for recycling;
- Impermeable geomembrane liners to prevent infiltration of acidic drainage into underlying materials;
- Waste rock or tailings maintained in a frozen state (in permafrost areas);
- Direct addition of lime or other alkaline substances;
- Raising of the water table to inhibit acid generation of materials disposed of below the water table;
- Use of tailings as mine backfill, or disposing of tailings in mined-out open pits.
Our team can help with: