Overview
Proper treatment of wastewater from mining operations (coal, copper, gold, silver, diamond, iron, precious metals, lead, limestone, magnesite, nickel, phosphate, oil shale, rock salt, tin, uranium, molybdenum) prevent soil contamination due to acidic or alkaline leaching of water or heavy metals. With the right system, the treatment of these waste streams is easy to manage.
How is ETP useful in mining and What is the process used?
This system removes solids and metals from groundwater and is upstream of the deionization process. The metal treatment process overview includes the following steps:
>to adjust the pH of the wastewater so that the metal forms an insoluble precipitate.
>Place the coagulant in the mixing tank to promote the collision of metal particles and form larger particles or flakes.
>The final addition of the flocculant in the form of a polymer allows the particles to bind to larger masses and deposit in a settling tank for collection/removal.
>You can then filter the water out of the sand basin to catch particles that are too small to set in the sand basin. The filter system used can include, for example, sand or activated carbon. The filter system should be backwashed regularly to prevent clogging. Then, during the backwash, the water flow is reversed and this water is returned to the stage 1 mixing tank.
>The settling stage uses sludge treatment, including dehydration, to remove excess water. This water can also be returned to the original mixing tank for treatment. Without proper wastewater treatment, there are some water-related challenges that can affect the efficiency of mining sites. This is because the wastewater from the mining industry are very acidic and have a lot of suspended solids.
Persistent problems in uncontrolled mining applications include:
-Mine spills and acid spills from heaps
-Groundwater pollution
-Very salty waste
-Aquifer poisoning
These problems are exacerbated by the fact that much of the otherwise beneficial mining work is already in areas with pressurized water supplies. Mining activities in these areas continue to deplete small amounts of freshwater.
From both an environmental and operational perspective, the best action is to prevent pollution from external sources and reuse mining wastewater as safely as possible. Fortunately, advanced wastewater treatment solutions allow mining wastewater to be reused for mining, irrigation and even drinking water.
Mining water treatment focuses on the treatment of process water. However, if you want to maximize water efficiency, it is also important to treat the water in combination with mine runoff and stormwater.
Regardless of the water source to be treated, the main goal is to remove metals, solids and other contaminants from the water and return the water to its optimum pH. Treatment of mining wastewater requires a combination of chemicals and mechanical filtration.
How to treat the mining waste water?
1: pH adjuster
One of the first things to do when treating mining wastewater is to bring the water back to its optimum pH. Not only is this important in itself to maintain water quality, but it also helps to precipitate the molten metal. By raising the pH of water, positively charged metal ions react with negatively charged hydroxide ions. This results in dense, insoluble metal particles that are easy to process.
When used in appropriate amounts, acidity regulators help reduce the acidity of mining wastewater and restore a more balanced pH. Although pH 7 is technically neutral, it is advisable to reset the mined water to pH 8 or higher before moving on to other treatments.
2: Coagulant
Once the pH of the water is set correctly, coagulants and flocculants can be used to remove small metal particles and suspended solids in the water and combine them into large chunks. This facilitates filter removal and mechanical removal.
3: Additional Chemicals
Acidity regulators, and coagulants are the main chemicals used in mining wastewater treatment, but in certain applications they are added to protect the system or prepare water for filtration. These include:
-Water softeners and ion exchangers
-Corrosion inhibitor
-Algae and biocides
-Filtration
After optimizing the water quality with the right chemicals, mechanical filtration can remove all particulate matter and certain types of organic matter. There are several machines available, but the main types of mechanical filtration equipment are:
-Centrifuge
-Filter press
-Belt press
Netsol Water has extensive experience in planning and installing this type of system and is pleased to be able to advise, design and build the right solution for your company. Contact us for more information on how we can help.
