- Heated brine increases efficiency and saves money for brine solution mining projects
- Plant operators should choose pipes that withstand high-temperature media.
- Steel and metal alloy pipes are expensive and susceptible to corrosion.
Solution mining is a mining technique that allows plant operators and owners to reach a mineral body without excavation or massive earth-moving operations. It significantly reduces the overall footprint and the visual footprint of the operation. In some cases—e.g., copper or gold solution mining—the solution used is a mixture of water and acids, which will require special environmental impact design and monitoring.
Brine solution mining is used to extract minerals such us potash, lithium, soda ash (sodium carbonate), boron, and more. But let’s focus on potash.
The idea behind solution mining is to introduce water to the ore body, dissolve the target mineral in its salt formation, and pump the brine back up to the processing facility to harvest the desired minerals. In the case of potash, NaCl is included in the ore body — this means that if it is, remove the salt and keep using fresh water for the extraction. Over time a huge amount of salt will also be produced as a by-product, wasting energy and resources.
Since NaCl has a different solubility than potash salt such as KCl, it is possible to use saturated NaCl brine to dissolve the potash without adding a salt pile at the processing side.
To further increase yield, some operations will heat the brine injected in to the ore body, as can be seen in the table below. This increases the solubility of KCl but does not add any NaCl.
Here is a brief summary of the benefits:
Targets potash directly — If you already have saturated brine going down the well, that liquid will only dissolve the potash because the liquid already has the maximum amount of salt it can absorb. Therefore, you’ll only be extracting your desired mineral out of the ore body.
Reduces water usage — and you’ll use less energy as a result. It will also reduce your footprint on additional salt that you’re extracting. Again, this is in case salt is not the product you want to use.
Increases efficiency — When you add heated brine to water, the brine content will increase the temperature of the media. When you increase the temperature, you’re also increasing the solubility of potash in the media.
Through this method of mineral processing, you get more product per volume of fluid that you send into the mine. That will increase the efficiency of the whole system.
This is a great way to leverage the physical properties of the salt in the ore body.
Pipe selection for brine solution mining
Solution mining in general, and especially involving concentrated brines, can challenge material selection. If the brine temperatures are low, then simple plastics like HDPE can be used, and have been used successfully. When temperatures increase, and especially if oxygen is present, alloys or rubber lined steel will be considered.
To avoid capital expenses, and to improve reliability of operations, there are some plastic options that can be considered — Pexgol being a proven material in that environment.
The pipe can hold temperatures up to 230°F/110°C, which is typically enough to withstand potash transportation.
And, of course, these pipes have no corrosion issues and little to no scale in the pipe.
It's not only important have good pipes leading to and from the injection wells. If you’re looking at the whole operation and the life of a plant, it’s crucial to have pregnant liquid lines that won’t corrode or crack.
Metal alloy materials are not only very expensive — the labour skill in welding them properly requires a high level of expertise.
Plastics are the way to go, if they’re designed to handle the temperatures, pressures and stresses of the mining operation.
Pexgol pipe has been used in brine solution mining since 1985. They’ve continuously been in service on a crystallizer, operating on temperatures that exceed 230°F/110°C, for the past 34 years.
To the well heads and back (and don’t forget the ponds)
In many cases the distance between the main processing plant and the injection wells, and/or ponds, is far. Using coiled pipes can significantly reduce installation time, labour hours, and improve reliability of both pregnant and barren lines due to a significant reduction in the number of connections. Pexgol pipes can be coiled up to 320ft/100m of a 14” diameter pipe.
If you want to learn more about brine solution mining and industrial pipe, you can talk to an expert.