Beckenanalyse 1:Economic Deposits in Sedimentary Environments [M.Geo.136a]

Part 2: Laterite, bauxite, karst-bauxite

István DunklSedimentology, University of Göttingen

http://www.sediment.uni-goettingen.de/staff/dunkl/University of Göttingen

[1] Definitions, Mining economy in brief

[2, 3] Deposits related to weathering / residual sediments[2] laterite, bauxite, karst-bauxite [3] Ni-laterite, regolith, gossan

[4] Placer deposits (gold, zircon + rutile + ilmenite + REE, diamond, tin)

[5] Chemical sediments (Fe- and Mn-sediments, Kupferschiefer, phosphate )

[6] Exhalative, infiltration and metasomatic deposits (SEDEX, Kupferschiefer,

MVT-type deposits, Carlin-type gold deposits, sandstone-type U-ores)

[7 - 9] Combustable materials

[7] coal, [8] oil and gas, [9] some oil provinces & non conventional hydrocarbon (oil shale,

tar sand, shale gas, gas hydrate)

[10] Mineral processing

Weathering

[Lounghnan]kaolinite !

[Robb, 2005]

Weathering

Chemistry of weathering

[Cissarz]

kaolinitealbite

[Robb, 2005]

Weathering

[Loughnan]

Lateritization

[Loughnan]

Weathering

[Edward and Atkinson]

Weathering

[Loughnan]

Lateritization

Lateritization

[Bauman et al.]

Lateritization

Lateritization

[Robb, 2005]

Laterites are products of intense subaerial rock weathering. They consist predominantly of mineral assemblages of goethite, hematite, aluminium hydroxides, kaolinite minerals and quartz. The SiO2 / (Al2O3+ Fe2O3) ratio of a laterite must be lower than that of the kaolinizedparent rocks. [Schellmann, 1982]

Bauxite is a member of the family of lateritic rocks. It is characterized by a particular enrichment of free aluminium hydroxide minerals.

Distribution of laterite on the surface of the Earth

[Gidigasu, 1976]

[Aleva, 1986]

The ferruginous bauxite deposit of Rio Norte, Brazil. The bauxite bed, 6 m thick, is overlain by an 8 - 10 m thick kaolinite bed, which in turn is covered by an Amazonian-type tropical forest.Photo: R.R. Anand.

Lateritic weathering section showingtransition of saprolite, on which the boy stands, a mottled zone within the lower part a relict colour pattern of core boulders, followed upward by a weakly indurated brown lateritebeneath a thin lateritic soil. Kerala, India. Photo: W. Schellmann.

Laterite

Lateritization

[Bárdossy and Aleva]

Lateritic bauxite

Kaolinite deposits

[Edward and Atkinson]

Typical textures of bauxites

Major bauxite minerals

[International Aluminium Institute]

Gibbsite Böhmite DiasporeComposition Al(OH)3 AlO(OH) AlO(OH)

Maximum Alumina Content [%] 65.4 85.0 85.0

Crystal System Monoclinic Orthorhombic Orthorhombic

Density [gcm-3] 2.42 3.01 3.44

Temp. for Rapid Dehydration [°C] 150 350 450

Major bauxite provinces

[Bárdossy and Aleva]

[Edward and Atkinson]

Bauxite deposits

Los Pijiguaos buaxite deposit – laterite on a dissected Late Cretaceous planation surface

[Robb, 2005]

Bauxite deposits

Lateritic bauxite

[Edward and Atkinson]

Geochemistry,

origin

[Bárdossyand Aleva]

Geochemistry of Sardinan bauxite

[Mameli et al., 2007]

Geochemistry of bauxites in N. Iran

[Esmaeily et al., 2010]

Geochemistry of Sardinan bauxite

[Mameli et al., 2007]

Geochemistry --- Scandium enrichment in a world-class lateritic deposit

[Chassé et al., 2017]

Karst bauxite

[Esmaeily et al., 2010]

Karst bauxiteand paleogeography

[Di Stefano and Mindszenty, 2000]

Karst bauxite deposits

Jenisey, Russia

Haut-Var, Provence, France

SiO2 content of a Transdanubian karst bauxite deposit

[Szantner et al., 1986]

Bauxite horizon in a hyatus in Sardinia

[Mameli et al., 2007]

Geochemistry of Sardinan bauxite

[Mameli et al., 2007]

Q: lateritic or karst bauxite?

[Bárdossy and Aleva]

siliciclastic

volcanic tuff

carbonate

bauxite

Schematic stratigraphy of Transdanubian Central Range

M i

l l i

o n

y e

a r

s

0

50

100

150

200

250

Terti

ary

Cre

tace

ous

Jur.

Tri.

Perm

.

Typology of zircon crystals (Pupin, 1980)

< 2%

2-5%

5-10%

10-20%

20-30%

30-40%

> 40%

Recsk-357 356 m Dudar DUD-2 and. PPDMonor 1/8

Zalatárnok Zt-1/8 and.

Kápolnásnyék-31140 m

Tóalmás-4/5M-172

Tükrösmajor-190 Nagykökényes-1/11M-168

Zircon typology of Eocene and Oligocene PAL-related magmatites

Rounded and euhedral zircon crystals in the NCA bauxite

Technological (geo-)chemistry

[Edward and Atkinson]

Quality

[Bárdossy and Aleva]

[Bárdossy and Aleva]

Technological

(geo)-chemistry

[U.S. Geological SurveyOpen-File Report 01-197]

Bauxite economy

aluminium

bauxite

History of Aluminium

[ALCOA and the Aluminum Institute]

1808: Sir Humphrey Davy (Britain) discovered the existence of the shiny metal we are sodependent on today and gave it a name - Aluminum. 1821: P. Berthier (France) discovered a hard, reddish, clay-like material containing 52 per cent aluminum oxide near the village of Les Baux in southern France. He called it bauxite - after the village. Today, we recognize bauxite as the most common ore of aluminum. 1845: Wohler determined the specific gravity of aluminum (2.7) which illustrated one of its unquie physical properties - it was extremely light in weight compared to most metals known at the time. 1854: Henri Sainte-Claire Deville (France) create the first commercial process for producing aluminum which - at that time - was more valuable than gold. 1855: A bar of aluminum was exhibited alongside the Crown Jewels at the Paris Exhibition. 1886: Two unknown young scientists, Paul Louis Toussaint Heroult (France) and Charles Martin Hall (USA), working separately and unaware of each other's work, simultaneously invented a new electrolytic process (eventually called the Hall-Heroult process) which is the basis for all aluminum production today. They discovered that if they dissolved aluminum oxide (alumina) in a bath of molten cryolite and passed a powerful electric current through it, molten aluminum would be deposited at the bottom. 1889: Freidrich Bayer (Austria), son of the founder of the Bayer chemical company, invented the Bayer Process for the large scale production of alumina from bauxite.

Bayer process

[ALCOA]

Complete extraction from diasporic bauxite requires stronger caustic solutions, in addition to higher temperatures and pressures. In practice this means that for deposits containing the more easily recovered gibbsite only, production costs are much lower than when boehmite or diaspore are present. The control of silica in the conventional Bayer Process is most important and in fact ores having reactive silica greater than 7% cannot be economically processed.Unlike quartz, which is considered virtually non-reactive at gibbsite extraction temperatures, some minerals, including kaolins, dissolve rapidly and the reaction of the silica can give rise to appreciable loss of caustic soda and aluminum.

Al2O3.xH2O + 2NaOH 2NaAlO2 + (x+1)H2O

2NaOH + Al2O3.3H2O 2NaAlO2 + 4H2O

Al2O3.2SiO2 + NaOH Na2SiO3 and desilication via precipitation.

Na2SiO3 + NaAlO2 Na2O.Al2O3.2SiO2

Na2CO3 + Ca(OH)2 CaCO3 + 2NaOH

Bayer process

Crushing and grinding

Settling: After washing to recover alumina and caustic soda, the remaining red mud is pumped into large storage ponds where it is dried by evaporation.

Digesting: The slurry is pumped to a digester where a solution of sodium hydroxide (caustic soda) dissolves AlOH minerals (under 30 atm pressure, between 200 and 240 °C). After the extraction stage the liquor (containing the dissolved Al2O3) must be separated from the insoluble red mud.

Bayer process

Calcination: Calcination is a heating process to remove the chemically combined water from the alumina hydrate. From precipitation, the hydrate is filtered and washed to rinse away impurities and remove moisture. The calcining kiln is brick-lined inside and gas-fired to a temperature of 1,100 °C. It slowly rotates and is mounted on a tilted foundation which allows the alumina to move through it to cooling eqipment. The result is a white powder like that shown below: pure alumina.

Precipitation: The clear sodium aluminate from the settling and filtering operation is pumped into the precipitators. Fine particles of alumina - called "seed crystals" (alumina hydrate) - are added to start the precipitation of pure alumina particles as the liquor cools. Alumina crystals begin to grow around the seeds, then settle to the bottom of the tank where they are removed to the calcination kilns.

Bayer process

Red mud (pH=13)

[redmud.org]

[vietnam.net]

[http://www.google.com/patents/WO2013104059A1?cl=en]

[nol.hu]

Material and energy consumption of the Bayer process

[Bárdossy and Aleva]

red mud

VGabrick

BTU = British Thermal Unit