Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphorus

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphorus

from Greek:

(φως = light,

φορέω = carry)

Phosphorus

• was discovered by Henning Brand, a Germanpharmacist and alchemist

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

• white phosphorus was formed after calcining theresidue under exclusion of air

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

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphorus

Phosphorescence

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphorus White phosphorus

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

• is highly flammable and pyrophoric (self-igniting)

• was used for fabrication of matches

• fire bombs and other weapons (additive tonapalm)

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

WhitePhosphorus

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

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphorus Red phosphorus

• Crystalline and amorphous modifications in adensity range of 2.0 – 2.4 g/ccm are know asred phosphorus

• Is formed from white phosphorus by heating to260°C for several hours under exclusion of air

• is highly flammable when combined with strongoxidants safety matches

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

RedPhosphorus

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

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphorus Black phosphorus

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

• Is formed from white or red phosphorus underhigh pressure

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

• Has semiconductor properties

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

BlackPhosphorus

Black phosphorus is the least reactive allotrope. Itis thermodynamically stable below 550° C and it isnot toxic.

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphate ore

Phosphorus is the 11th most abundant element inthe lithosphere occurring as phosphate commonlyas an inorganic mineral phase or as an organicmolecule.

Phosphate rock is the only economic source for P

•Marine sedimentary phosphorite formed oncontinental shelves by oceanic upwelling of coldwater 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)

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphate ore Minor sources include:

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

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

•Recycling product: slag (Thomas converter)

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

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Another source ofphosphorus

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphate ore World production peaked at 166 million tons ofphosphate rock 1988, subsequently falling back toca. 140 million tons :

•80% from deposits of sedimentary origin

•17% form igneous rocks and their weatheringderivatives

•Remainder: residual sedimentary and guanodeposits

•Economically produced phosphate ore contains 20– 30% P2O5

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphateexploitation

• Open pit mining methods with walking draglines(Florida)

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

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

• Sub-level open stoping (Kola Penninsula)

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

• Magnetic separation to remove iron minerals

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

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphateexploitation

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphate rockproduction andresources

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphateminerals

Apatite (Fluorapatite)

From Greek “apatao” =I’m misleading

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphateminerals

Autunite

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphateminerals

Turquoise

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphateminerals

Nearly 400 phosphatecompounds are known,but only few controlphosphateconcentration in naturalsystems

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

PhosphorusPhosphorus is a unique element:

•A key element in many physiological and biochemicalprocesses

•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 plantproductivity

•(Historically: overcome by recycling of manure)

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphates

Phosphate uptake byplants

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Use ofphosphates

Phosphate richfertilizers used todramatically increaseglobal agriculturalproduction

Cereals are estimated to account for 55% offertilizer use worldwide; wheat 20%, corn 14%, rice13%, barley 4%

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphoric acidPhosphoric acid is the largest inorganic acidproduced and consumed by value (and onlysecond to sufuric 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……..

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

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

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

• Hydrogen fluoride reacts with silicates to fluorosilic acid

SiO2 + 6HF H2SiF6 + 2H2O

• Formation of 1 ton of P2O5 as wet process acid consumes3.3 – 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 gypsumto be treated as waste

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Phosphates in theenvironment

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

• Ban of phosphate base detergents inSwitzerland (since 1985) caused a reduction of70% of phosphate input

• Agricultural phosphate release to natural watersusually cannot be attributed to leaching offertilizers

• But rather to increased use of phosphate-richmanure

• Phosphate-rich manure is mainly aconsequence of feeding with off-site producedcattle feed

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Challenges forearth scientists

• Improve ability to limit mobilization ofphosphorus from agricultural and other humansources to natural waters

• Developing ‘designer’ fertilizer with formulationsthat allow better control of phosphorus release

• Methods to recycle phosphorus from waste(sewage sludge and effluents)

• Taking advantage in low solubility of phosphateminerals and focus research to design methodsto immobilize toxic and radioactive waste

Applied Mineralogy and Non-Metallic Resources I Phosphorus and phosphate

Fertilizer fromincineratedsewage sludge

• Use of sewage sluge as fertilizer is not allowedin Switzerland (since 2008)

• Sewage is incinerated and disposed in landfills

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

• A research project started by the Paul-Scherrer-Institute led to development of athermochemical treatment of the ash forseparation from heavy metals

Result: fertilizer granulate with solublephosphorus