Super cool crystallization ponds

By Mark Machado | October 31, 2016

It's exciting to see new technologies emerge when you’re investigating complex industrial challenges. Especially when they give rise to innovative perspectives and novel solutions that run counter to the conformist approaches and practices the industry is currently using.

Crystallization ponds are a case in point. Historically, these pond systems offered a relatively low-cost solution to the recovery of potash, lithium, and other valuable minerals from brines. They’re ideally suited to areas where land is available and the climatic conditions for the operating site are favorable—low ambient temperatures, little precipitation, and/or a high potential for natural evaporation.

The vast majority of these older pond operations were constructed in a different era, 30 or 40 years ago. Back then, we didn’t have the computational tools and know-how that’s available today to optimize the design. Some of these installations were created using the same approach that was used for tailings or storm water recovery ponds. They didn’t consider the physical attributes and geometry of a system, and how that could be configured to maximize pond utilization, production, and recovery.

When we went looking to design new crystallization ponds we had two choices. Maintain the status quo and mimic what had been used in the past. Or, go back to the drawing board to find a smarter, more economical way of doing it.

We chose the latter.

We began by delving into the chemistry, heat, mass-transfer phenomena, and meteorological effects. We moved on to modeling the thermal-hydraulic characteristics of traditional pond systems, and that’s when the light bulb came on. We found that by optimizing the pond configuration, bathymetry, and other geometric parameters, we could significantly increase the pond’s productivity for a given feed flow. We validated our models through an extensive work program at an operational solution mine with cooling-crystallization-pond systems one for which a patent was filed and recently granted.

The technology developed has tremendous implications for commercial use. One of the largest opportunities we see is in the potash space. It could be a game changer for some solution mining projects or flooded conventional mines in cold climates like Saskatchewan, Russia, and western China.

In potash-solution mining, a heated solvent is typically injected into the deposit. It dissolves the potash-bearing minerals and produces a rich brine that is pumped to the surface for processing. Then, a circuit of mechanical evaporators and crystallizers is used to remove the impurities from the solution-mined brine and produce the potash product.

Crystallization ponds are usually used in parallel with this process, or as an additional stage to naturally cool the brine and facilitate the precipitation of potash from its impurities at a lower cost. With our patented design, we can enhance the heat transfer within a smaller footprint compared to conventional pond designs. Overall, that translates into increased production, better operating efficiency, and a higher revenue potential for existing pond operations. A leaner pond design is also less expensive to set up and operate—something that’s especially attractive to new developers trying to gain a foothold in the potash market.

But the design isn't limited to potash. It can be applied to a wide array of mineral salts and commodities, like lithium and phosphate. It can even be used to recover valuable minerals from plant-waste bleed streams and serve as a heat sink for industrial cooling processes.

Leaner, more efficient, cost-effective mineral recovery. Smaller environmental footprints. And a boost for both existing players and new entrants to the industry. When you’re willing to look for a better way to do something, you just might find it. Sometimes, in spades.