Pre-treating Dead Sea water before entering evaporation ponds

ICL, the Seeker for this Wazoku Crowd Challenge, is looking for improved technology to pre-concentrate Dead Sea Water before entering the series of solar evaporation ponds.

With its salinity of almost 30%, Dead Sea water is a great source for minerals production. One of the most commercially valuable among them is Carnallite, a raw material for potash production.

Typically, Carnallite is extracted by sequential evaporation, when increasingly concentrated Dead Sea water moves through a series of evaporation ponds. As the brine composition reaches a certain point, Carnallite starts precipitating.

Unfortunately, initial composition of Dead Sea water leads to precipitation of Carnallite along with Halite only in ~1/3 of the area of solar evaporation ponds. It means that in ~2/3 of the evaporation ponds, only Halite, a by-product, precipitates. In addition, the evaporation process doesn’t allow the extraction of all Carnallite (the end-brine has a potential of precipitating additional Carnallite).

ICL is therefore looking for a novel approach to pre-concentrating Dead Sea water and/or removing Na+ ions before entering the evaporation ponds. In that way, Carnallite extraction would be more efficient than currently available, while not increasing the extent of evaporation, and reducing Halite removal costs.

This is a Prize Challenge which requires a written proposal to be submitted. There will be a guaranteed award pool of $15,000, with at least one award of $5,000 or larger and no award being smaller than $2,500. Award distribution (or allocation) will be contingent upon the theoretical evaluation of the proposals. By submitting a proposal, the Solver grants the Seeker a right to use any information included in their proposal.

With its salinity of almost 30%, Dead Sea water is a great source of minerals.

One of the most commercially valuable among them is Carnallite, a hydrated potassium magnesium chloride with formula KCl.MgCl₂·6(H₂O), an important source of potash.

Typically, Carnallite is extracted from Dead Sea water by the process of sequential evaporation. During this process, the increasingly concentrated brine moves through a series of evaporation ponds, while its saltiness grows from ~28% in the first evaporation pond to 36% in the last.

The first mineral to precipitate is Halite (NaCl), or common salt. This occurs immediately because the water is already saturated with Halite. Approximately 2/3 of the evaporation pond area is used to precipitate only Halite.

As evaporation continues and the water concentration reaches the “Carnallite point”: Carnallite (KCl.MgCl₂·6(H₂O)) begins to precipitate too. Approximately 1/3 of the total evaporation pond area is used to precipitate Carnallite. Importantly, Carnallite co-precipitates with Halite.

This process suffers from three major problems. First, the area of evaporation ponds to deal with Carnallite precipitation is only 1/3 of the total evaporation pond area; 2/3 of the area is used only to get rid of Halite. Evaporation area is a limited resource.

The second problem is that the end brine (brine from the last evaporation pond to be directed back to Dead Sea) has potential to precipitate more Carnallite, but it requires additional evaporation.

Third, the resulting Carnallite is heavily contaminated with Halite, which in this instance represents an undesirable by-product.

We tried to improve the process by pre-concentrating Dead Sea water. Several approaches have been used, with forward osmosis, absorption, and distillation among them. All of them turned out to be inefficient for our purpose, mainly due to the lack of scalable technology and/or high costs.

We therefore want to design a novel approach to either pre-concentrate Dead Sea water or remove Na+ ions from Dead Sea water before entering the solar evaporation ponds — so that Carnallite extraction would be more efficient — while not increasing the extent of evaporation.

More specifically, we expect the proposed technology to be able to pre-concentrate Dead Sea water from about 280 g/kg of Total Dissolved Solids (TDS) to about 285 g/kg (density of ~1.24 to ~1.25), or to reduce sodium ion from about 60 g/kg in Dead Sea water to 55 g/kg. At the same time, we expect the proposed technology not to engage any additional sequential evaporation or increase the water consumption.

We’re willing to consider proposals based on forward osmosis, absorption, and distillation but only if a dramatic improvement in performance and scalability was demonstrated.

SOLUTION REQUIREMENTS

ICL is open to any innovative approach for as long as the proposed solution meets the following major Solution Requirements:

1. The proposed solution should result in pre-concentrating Dead Sea water by 5 g/kg TDS (from 285 g/kg to 280 g/kg), or by reducing Na+ concentration in Dead Sea water by about 5 g/kg (from 60 g/kg to 55 g/kg).
2. The proposed solution should not increase the extent of evaporation.
3. The proposed solution should not depend on any changes in external temperatures.
4. The proposed solution should use an existing technology that is scalable to hundreds of thousands of tons of Dead Sea water.
5. The proposed solution should be feasible with highly concentrated brines and take into account Halite precipitation.
6. The proposed solution should consider the energy demands of the technology, favoring low energy consumption technologies.
7. The proposed solution should be completely sustainable, i.e., it should not introduce any additional environmental hazards, nor represent occupational risks to the operator.

Awards:- $15,000

Deadline:- 24-04-2024

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