Arab Potash brings Dead Sea to life

By
Published: Sunday, 24 January 2010

IM reviews Arab Potash’s mine to market chain to see how it has established itself as one of the leading potash producers in the Middle East

In terms of volume it is very difficult for brine potash producers to compete with the hard rock miners that dominate the industry. The volumes of brine liquid are immense and the concentration of potash considerably lower compared with its rock counterpart.

Jordan based Arab Potash Co. (APC), however, has positioned itself as the second largest producer of the predominately fertiliser mineral in the Middle East and all from extracting and processing potash from the Dead Sea.

In terms of potash production from brine, APC is the second largest in the world with a 2.5m. tpa output. It is sandwiched between the leading producer, Israeli Chemical Ltd with a 5m. tpa capacity and SQM SA of Chile which has the ability to mine 550,000 tpa from its operation in the Atacama Desert.


The Dead Sea is one of the world’s
richest sources of dissolved minerals
such as potash, magnesia and lithium.


Potash from the Dead Sea

The process commences at the brine pumping station where four intake pumps with a capacity of around 18 m3/s deliver about 300m. tpa of the Dead Sea brine to salt ponds where the brine is further concentrated through solar evaporation.

At the end of the salt ponds, the brine flows by gravity into a pond. From there the brine is pumped to the first carnallite pond and then it flows by gravity to the remaining ponds. Carnallite production capacity from this system is over 9m. tpa of pure carnallite a year.

Carnallite deposited in ponds is collected via specially designed equipment called harvesters that cut the precipitated carnallite and pump it to the plants as a slurry of solids (carnallite and sodium chloride) and brine. Presently, there are eight operating harvesters each of which can deliver a design flow rate of 720 m3/h.

Carnallite slurry is processed in a two-stage decomposition process to remove the magnesium chloride, thereby leaving a potassium chloride and sodium chloride mixture called sylvinite.

The sylvinite cake is then leached with heated brine to extract potassium chloride from sylvinite. Potassium chloride dissolves leaving behind sodium chloride solids. The hot brine is clarified in a hot thickener, the overflow of which is pumped to the crystallisation process and the underflow slurry containing sodium chloride crystals is centrifuged and the resulting solids are sent to tailing.

The crystallisation process involves cooling the saturated hot brine in a six-stage vacuum crystallisers system that produces potash crystals. Potash slurry from the last stage crystalliser is partially dewatered in hydro cyclones, and the underflow of the cyclones is sent to centrifuges for further dewatering.

The cake from the centrifuges is then dried in a rotary dryer, cooled and screened into standard and fine product grades. Portions of these grades can be diverted into a compaction plant of a granular potash capacity of 150,000 tpa.


The carnallite ponds and a harvester
at the Safi potash extraction facility in
Jordan. Courtesy Arab Potash Co.


Cold crystallisation plant

Here the carnallite slurry is first screened to separate the high-grade coarse carnallite which is then fed directly to the cold crystallisers. The undersize material is then beneficiated by flotation to separate sodium chloride. The product of the flotation unit is then dewatered in the centrifuges which produce the fine carnallite cake.

Both coarse and fine carnallite are decomposed in a two-stage crystalliser together with water. Potassium chloride crystals form in the crystallisers. The discharge slurry from the crystallisers is then screened to remove large particles of sodium chloride which are pumped to tailings area. The remaining product is then leached and dewatered to remove adhering high magnesium chloride brine and then dried in a co-current oil-fired rotary dryer. Potash product is then cooled in a rotary cooler before being sent to the warehouse.

This plant utilises the hot crystallization process. Fine potash collected from APC’s facilities is dissolved with water and heated up to 100ºC.

The saturated brine is then sent to the draft tube baffle type (DTB) vacuum crystalliser where adiabatic cooling of the solution takes place to produce crystals. The product of the crystalliser is pumped to a hydro-cyclone then to a centrifuge to give a cake of 5% moisture. The cake is dried and cooled in a fluidized bed dryer/cooler system.


Aqaba Port where Arab Potash Co.
can load two vessels at a rate of
2,000 tph. Courtesy Arab Potash Co.


Logistics

Loading

Potash produced by the plants is conveyed to the warehouse via belt conveyors. At the warehouse, a tripper is used to pile potash according to type. Usually standard and fine potash grades are stored in the warehouse, while granular potash is directly transported to the shipping bin.

A reclaiming system is utilised to convey the stored product to the shipping bins. Loaders transfer the stored potash to pan feeders feeding a belt conveyor that feeds the shipping bins. There are three shipping bins at Safi Site: one for standard, one for fine and the third one is for granular potash.

From the shipping bins, potash is dispatched to the loading trucks.

Potash is hauled to over 200km to APC’s Aqaba terminal. Each truck unit consists of two combined semi-trailers, a converting dolly and a truck tractor. APC has a fleet of 70 mack truck tractors and 75 trailers.

Plans are in progress to replace the steel semi-trailers with aluminum semi-trailers. The GCW (Gross Combination Weight) of the train shall not exceed 77 tonnes to conform to the governmental regulations.


Arab Potash Co.’s new felt of trucks
77 tonne trucks which are now made
of aluminium instead of steel for a lighter
load as per government directive.


The port

The Aqaba site employs two storage sheds, each with a nominal capacity of 125,000 tonnes and a total nominal capacity of 250,000 tonnes.

Potash transported from Safi is unloaded at Aqaba terminal and is conveyed from both unloading facilities to the storage sheds is stacked (500 tph) in multiple stockpiles: in Store Shed No. 1 by means of two boom stackers, and in Store Shed No.2 by means of a single boom stacker.

Each storage shed is equipped with a portal scraper reclaimer, which reclaims the potash from the stockpiles and loads it onto a system of reclaim conveyors.

A jetty for loading ships is shared with Jordan Phosphate Mining Co. Aqaba potash warehouses are linked to the industrial ports berths especially designed for exporting bulk materials through two handling lines, each of which is connected with ship loader. Thus, two vessels from both warehouses can be loaded at a rate of 2000 tph for each vessel at the same time.

The reclaiming system ensures physical uniformity, guarantees reduced segregation and prevents caking. De-dusting, oil treatment and new screening units are installed to remove any fine particles and to reduce dust emissions during loading vessels at rates up to 700 tph.



Profile: Arab Potash

Company: Arab Potash Co.

Location: Jordan

Founded: 1956

Minerals mined: Potash

Source: Dead Sea brine

Employees: ~2,000

Plant capacities:

1983: 1.2m. tpa

Late 1980s: 1.4m. tpa

1994: 1.8m. tpa

2008: 2m. tpa

2010: 2.4m. tpa

Plant location: Safi, 110km south of Amman

Additional offices: Safi and Aqaba

Markets





Logistics flow diagram