Listing Description:
Phosphorite, phosphate rock or rock
phosphate is a non-detrital sedimentary
rock which contains high amounts of phosphate minerals.
The phosphate content of phosphorite (or grade of phosphate rock) varies
strongly, from 4%[1] to 20% phosphorus pentoxide (P2O5).
Detailed Description:
Marketed phosphate rock is enriched ("beneficiated")
to at least 28%, often more than 30% P2O5. This occurs
through washing, screening, de-liming, magnetic separation or flotation.[1] By comparison, the
average phosphorus content of sedimentary rocks is less than 0.2%.[2] The phosphate is
present as fluorapatite Ca5(PO4)3F
typically in cryptocrystalline masses (grain sizes
< 1 μm) referred to as collophane-sedimentary apatite deposits of
uncertain origin.[2] It is also present
as hydroxyapatite Ca5(PO4)3OH
or Ca10(PO4)6(OH)2, which is often
dissolved from vertebrate bones and teeth, whereas fluorapatite can originate
from hydrothermal veins. Other sources also
include chemically dissolved phosphate minerals from igneous and metamorphic rocks. Phosphorite
deposits often occur in extensive layers, which cumulatively cover tens of
thousands of square kilometres of the Earth's crust.[3]
Limestones and mudstones are common
phosphate-bearing rocks.[4] Phosphate rich
sedimentary rocks can occur in dark brown to black beds, ranging from
centimeter sized laminae to beds that are several meters in thickness. Although
these thick beds can exist they are rarely only composed of phosphatic
sedimentary rocks. Phosphatic sedimentary rocks are commonly accompanied by or
interbedded with shales, cherts,
limestone, dolomites and sometimes sandstone.[4] These layers contain
the same textures and structures as fine-grained limestones and may represent diagenetic replacements
of carbonate minerals by phosphates.[2] They also can be
composed of peloids, ooids, fossils, and clasts that are made up of apatite.
There are some phosphorites that are very small and have no distinctive
granular textures. This means that their textures are similar to that of
collophane, or fine micrite-like texture. Phosphatic grains may be
accompanied by organic matter, clay minerals, silt sized detrital grains,
and pyrite. Peloidal or pelletal phosphorites occur normally;
whereas oolitic phosphorites
are not common.[4]
Phosphorites are known from Proterozoic banded iron formations in Australia, but are more
common from Paleozoic and Cenozoic sediments. The Permian Phosphoria Formation of the western United States represents some 15
million years of sedimentation. It reaches a thickness of 420 metres and covers
an area of 350,000 km2.[2] Commercially mined
phosphorites occur in France, Belgium, Spain, Morocco, Tunisia and Algeria. In the United
States phosphorites have been mined in Florida, Tennessee, Wyoming, Utah, Idaho and Kansas.
Production and use
Deposits which contain phosphate in quantity and
concentration which are economic to mine as ore for their phosphate
content are not particularly common. The two main sources for phosphate are guano, formed from bird droppings, and rocks
containing concentrations of the calcium phosphate mineral, apatite.
Phosphate rock is mined, beneficiated, and either
solubilized to produce wet-process phosphoric acid, or smelted to
produce elemental phosphorus. Phosphoric acid is
reacted with phosphate rock to produce the fertilizer triple superphosphate or with anhydrous ammonia to produce the ammonium phosphate fertilizers.
Elemental phosphorus is the base for furnace-grade phosphoric acid, phosphorus
pentasulfide, phosphorus pentoxide, and phosphorus trichloride. Approximately 90% of phosphate rock production is used for fertilizer and animal feed
supplements and the balance for industrial chemicals.
Froth flotation is used to
concentrate the mined phosphorus to rock phosphate. The mined ore
slurry is treated with fatty acids to cause calcium
phosphate to become hydrophobic.
For general use in the fertilizer industry, phosphate
rock or its concentrates preferably have levels of 30% phosphorus pentoxide (P2O5),
reasonable amounts of calcium carbonate (5%), and <4% combined iron and aluminium oxides.
Worldwide, the resources of high-grade ore are declining, and the beneficiation
of lower grade ores by washing, flotation and calcining is becoming more
widespread.
In addition to phosphate fertilisers for agriculture, phosphorus from
rock phosphate is also used in animal feed supplements, food preservatives,
anti-corrosion agents, cosmetics, fungicides, ceramics, water treatment and
metallurgy.
As of 2006, the US is the world's leading producer
and exporter of phosphate fertilizers, accounting for about 37% of world P2O5exports.[12] As of 2008, the
world’s total economic demonstrated resource of rock phosphate is 18 gigatonnes,
which occurs principally as sedimentary marine phosphorites.
PRICES
$93/MT OR $0.04/IB
For more information:
mobile: +2348039721941
contact person: emeaba uche
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