While there are various rich mineral deposits buried in the earth, it may be uneconomic to mine these mineral deposits due to the expensive cost of reaching and extracting them. This is a common problem with traditional mining techniques.
However, the innovation of in-situ recovery (ISR) allows for selective mining with minor environmental disturbance.
ISR is an approach to mineral extraction that combines drilling, rock fracturing, and chemical leaching at the drill site. This allows for minimal surface disturbance as the solution is pumped into the ore body and the metals are dissolved into the leach solution. This solution is pumped to the surface for processing.
This process is widely used in uranium in-situ recovery and gold and copper mining, but this process also has potential for other minable ores.
This article will run you through the differences between ISR leaching methods and conventional mining methods.
The Development of the ISR Method
ISR developed in the 1970s as the mining industry searched for an affordable way to access large uranium deposits. Before this, the uranium recovery industry in Texas was dominated by conventional mining methods. Even until the late 1980s, traditional methods were still used.
It wasn’t until recently that ISR methods gained more popularity. This method makes recovery possible without disturbing the natural surface, generating dust, and producing waste tailings. It is a more environmentally friendly method.
Conventional Recovery Methods
Before the ISR method, the conventional method was used to recover minerals.
Conventional recovery methods include an open pit, milling, heap leaching, and underground mining, all more damaging to the landscape and the environment. In open-pit mining, the landscape is excavated to expose an extensive ore deposit area. Then the ore is extracted with heavy machinery.
This process disturbs the surface significantly, and tunnels are dug to reach and remove the uranium ore.
The ore is then ground into small particles for further processing. The pulverization process generates dust containing naturally occurring radioactive materials. This process also uses strong acids and chemicals to extract the uranium from the pulverized ore.
The waste materials produced from this process also contain uranium, heavy metals, and naturally occurring radioactive materials making it a high-waste process.
How ISR Recovery Works
Unlike the conventional method, ISR recovery uses the following steps:
- A solution is injected into the underground zone bearing the uranium ore. This solution consists of oxygen, hydrogen peroxide, and other oxidizing agents in water.
- The uranium that encounters this solution dissolves into the solution.
- This solution with dissolved uranium is pumped back into the surface for recovery.
- The solution passes through an ion-exchange column where the uranium is absorbed, and the uranium-free solution is pumped out.
- A stripping solution is poured into the ion-exchange column to redissolve the uranium.
- This uranium-bearing solution is treated to turn it into a solid form.
- This solid form of uranium is isolated and transferred somewhere else for processing.
This method has less radioactive waste material and has minimum damage to the mined surface.
In situ leach mining is an innovative approach to mining methods that uses less surface disturbance while recovering uranium.
This method uses a solution to dissolve uranium ore and pumps it to the surface for more processing. The resulting waste is less harmful and less radioactive than conventional mining methods.
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