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
