applied mineralogy and non-metallic resources i...

1

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphorus


Phosphorus

Examples ofphosphorus in food additives

Cola

Backing powder

2


Phosphorus

from Greek:

(φως = light,

φορέω = carry)

Phosphorus

• was discovered by Henning Brand, a German pharmacist and alchemist

• he was searching for the Philosopher’s Stone, concentrating urine by evaporation

• white phosphorus was formed after calciningthe residue under exclusion of air

• white phosphorus showed an unique property phosphorescence (glowing in the dark)

• http://www.youtube.com/watch?v=GIGOF_In9BM&feature=related


Phosphorus

Phosphorescence

3


Phosphorus White phosphorus

• was first used as a drug due to it’s unique property

• is highly flammable and pyrophoric (self-igniting)

• was used for fabrication of matches

• fire bombs and other weapons (additive to napalm)

• highly toxic


WhitePhosphorusin weapons

4


WhitePhosphorus

http://youtu.be/QaUIFZCCHiE

White phosphorus is the least stable, most reactive, more volatile, less dense and most toxic of all allotropes of phosphorus


Phosphorus Red phosphorus

• Crystalline and amorphous modifications in a density range of 2.0 – 2.4 g/ccm are know as red phosphorus

• Is formed from white phosphorus by heating to 260°C for several hours under exclusion of air

• is highly flammable when combined with strong oxidants safety matches

5


RedPhosphorus

http://www.youtube.com/watch?v=CsvSUAwq0uM&list=LPGstqDNdS354&index=9&feature=plcp

Red phosphorus is less reactive than the white allotrope, and it is not toxic.


Phosphorus

Black phosphorus

• 3 crystalline and 1 amorphous modification with a density of 2.69 g/ccm

• Is formed from white or red phosphorus under high pressure

• It is gray-black and the structure resembles to that of graphite

• Has semiconductor properties

6


Phosphate ore

Phosphorus is the 11th most abundant element in the lithosphere occurring as phosphate commonly as an inorganic mineral phase or as an organic molecule.

Phosphate rock is the only economic source for P

• Marine sedimentary phosphorite formed on continental shelves by oceanic upwelling of cold water enriched in nutrients (North Africa, W-USA, Mexico, Brazil, China, Vietnam)

• Deposits formed by disintegration of phosphoriterocks and reworking in sea and streams (Florida)

• Magmatic resources: magnetite-apatite (Kiruna) apatites from nepheline syenite (Khibiny, Kola) pyroxenite and carbonatite (Palabora, SA)


Phosphate ore

Phosphorite

7


Phosphate rockMorroco


Phosphate ore Minor sources include:

• Guano: thick accumulation of bird excreta reacting with limestone (Christmas Island, Nauru)

• Aluminous phosphates from weathering of phosphate rock with local significance (Senegal)

• Recycling product: slag (Thomas converter)

• Earlier is CH: ground bones, but also marls and sandy layers (Gault, Gemsmättlischichten)

8


Guano


Another source of phosphorus

9


Phosphate minerals

Apatite (Fluorapatite)

From Greek “apatao” = I’m misleading


Phosphate minerals

Autunite

10


Phosphate minerals

Turquoise


Phosphate minerals

Nearly 400 phosphate compounds are known, but only few control phosphate concentration in natural systems

11


Phosphate exploitation Phosphate mine, Negev


Phosphate exploitation

Phosphate miningin Togo

Photo: Alexandra Pugachevskaya

12




• Open pit mining methods with walking draglines (Florida)

• Coal mining-like techniques with blasting and removal by dragline/shovel (Morocco, Tunisia)

• Underground methods for steeply dipping deposits include room-and-pillar (North Africa)

• Sub-level open stoping (Kola Penninsula)

• Washing, crushing, sizing and flotation is common in order to increase BPL to 60 – 88%

• Magnetic separation to remove iron minerals

• Slurries need screening and hydrocycloning to remove clay prior to flotation (Florida)


Phosphorus contentGrade of commercial phosphate rock is usually defined in terms of its phosphorus pentoxide (P2O5) content.

The phosphorus concentration in phosphate rock is also commonly expressed in terms of tricalcium phosphate Ca3(PO4)2 known in the trade as "Bone Phosphate of Lime" or BPL. This term originated when tricalcium was thought to be the main constituent of bone and phosphate rock.

13


Phosphate rock production


Phosphate ore

80% sedimentary origin

17% igneous rocks and their weathering prod.

Remainder: residual sedimentary, guano

Economically produced phosphate ore contains 20 – 30% P2O5

World production peaked at 166 million tons of phosphate rock 1988, subsequently falling back to ca. 140 million tons but has increased again:

14


Phosphate rock production


Use of phosphates

Phosphate rich fertilizers used to dramatically increase global agricultural production

http://www.stonegateagricom.com/s/Videos.asp

Cereals are estimated to account for 55% of fertilizer use worldwide; wheat 20%, corn 14%, rice 13%, barley 4%

15


Phosphate fertilizers

• Single superphosphate (SSP)

• Triple superphosphate (TSP)

• Diammonium phosphate (DAP)

• Monoammonium phosphate (MAP)

• Ground phosphate rock


Phosphoric acid • Finely ground phosphate rock is mixed with water and treated with sulfuric acid. The basic reaction is:

Ca5(PO4)3F + 5H2SO4 + 10H2O 5CaSO4 · 2H2O + 3H3PO4 + HF

• Hydrogen fluoride reacts with silicates to fluorosilicic acid

SiO2 + 6HF H2SiF6 + 2H2O

• Formation of 1 ton of P2O5 as wet process acid consumes 3.3 – 3.4 t of phosphate rock (70% BPL)

• By-products include 1.7 t phosphogypsum

• High content of P, F, Cl, U, Th, REE requires this gypsum to be treated as waste

16


Phosphoric acid

Phosphoric acid is the largest inorganic acid produced and consumed by value (and only second to sulfuric acid in terms of volume).

• Fertilizer

• Feedstock of phosphates and fertilizers

• Cattle feed additives

• Food additives

• Detergent additives

• Acid cleaners

• Hardener for paints and varnish

• Synthetic rubber

• Etc……..


Prices

Phosphate rock grade expressed as %P2O5 or as BPL (Bone Phosphate of Lime)

%P2O5 x 2.185 = %BPL

17


Key element Phosphorus is a unique element:

• A key element in many physiological and biochemical processes

• An essential nutrient for all life forms

• Converts energy to a usable form for food and fiber

• Uptake by most living organisms from natural waters

But,

• Low solubility of phosphate minerals

P is a limiting element for animal and plant productivity

• (Historically: overcome by recycling of manure)


Phosphates

Adenosine Triphosphate (ATP); energy gain when end phosphate is released to form ADP

A phosphate group is attached when a cell needs to store energy.

molecular “rechargeable battery”

18


Phosphatecycle


Phosphates in the environment

• Increase of phosphate content in sewage due to use of phosphate based detergents eutrophication of rivers and lakes

• Ban of phosphate base detergents in Switzerland (since 1985) caused a reduction of 70% of phosphate input

• Agricultural phosphate release to natural waters usually cannot be attributed to leaching of fertilizers

• But rather to increased use of phosphate-rich manure

• Phosphate-rich manure is mainly a consequence of feeding with off-site produced cattle feed

19


Limited resources

2007 estimation:the supply of phosphorus may last only 345 years

Other estimates forecast a "peak phosphorus" in 30 years reserves will be depleted in the next 50 to 100 years

http://www.youtube.com/watch?v=Y17HqUsaoj8&feature=related


Cleantech

Separation of urine from solid using No-mix toilets

Urine accounts for 1% of total wastewater but contains 80% of nutrients

“The Europeans are certainly leading the way in this area, in Switzerland trials with NoMix toilets have been quite successful. Apparently the majority of the Swiss people interviewed said they had no problem with it, even the men, who had to sit down to spend a penny!”

20



Fertilizer from incinerated sewage sludge

• Use of sewage sludge as fertilizer is not allowed in Switzerland (since 2008)

• Sewage is incinerated and disposed in landfills

• 40 – 90 g P per kg ash from incinerated sewage sludge 6100 t P in Switzerland per year

21


Source: BSH Umweltservice AG, Sursee



22





23


Results:

The large-scale production test at the decommissioned incineration plant in Bern has show:

• Sewage sludge ash is a source for phosphorus

• Recycling rate with LEACHPHOS procedure is ca. 90%

Further:

• A mono incineration plant was built in Werdhölzli, Zürich and is in operation

• The sewage sludge of all waste water treatment plants in Kt. Zürich incinerated there

• The sewage sludge ash is currently disposed in Teuftal Kt. Bern

• Production of phosphoric acid is from sewage sludge ash is more likely than production of fertilizer (for legal reasons)

applied mineralogy and non-metallic resources i...

Documents