Transcript INDUSTRIAL MINERALS FLOTATION TECNOLOGIES

INDUSTRIAL MINERAL
CONCENTRATION TECNOLOGIES
Prof.Dr. Muammer KAYA
Osmangazi University
Eskisehir-TURKEY
2007
From raw material
To Final Product
Principles of Flotation
Flotation concentration method utilizes
the differences in physico chemical
surface properties of particles.
Hydrophobic (water repellent) particles
float with air bubbles to form a froth.
Wetted hydrophilic particles sink.
Hydrophobicity increases with the
contact angle btw particles and bubbles.
Chemical reagents are used in flotation.
Flotation is a selective separation
process.
Flotation is the most important and
versatile mineral processing technique
used in mining industry.
APPLICATION OF FLOTATION
• Flotation can be successfully applied to
both metallic and industrial minerals given
below for removing impurities and improving
quality:
• Apatite/Phosphate, Barite, Calcite, Dolomite,
Feldspar, Fluorspar, Graphite, Iron Ore,
Kyanite, Magnesite, Monazite, Potash,
Pyrochlore, Quartz/Silica Sand, Scheelite etc.
MECHANICAL FLOTATION MACHINE
Froth flotation is achieved when particles are separated based on their
surface potential. Hydrophobic particles are recovered to the froth,
whereas hydrophilic particles are discharged with the tailings stream.
PHOSPHATE MINERALS
•
•
•
•
•
•
Phosphate minerals are those minerals that contain the tetrahedrally coordinated
phosphate (PO43-) anion along with the freely substituting arsenate (AsO43-) and vanadate
(VO43-). Chlorine (Cl-), fluorine (F-), and hydroxide (OH-) anions also fit into the crystal
structure.
The phosphate class of minerals is a large and diverse group, however, only a few species
are relatively common.
Examples include:
triphylite Li(Fe,Mn)PO4
monazite (Ce,La,Y,Th)PO4
Apatite group Ca5(PO4)3(F,Cl,OH)
–
–
–
•
•
•
•
•
•
•
•
•
•
hydroxylapatite Ca5(PO4)3OH
fluorapatite Ca5(PO4)3F
chlorapatite Ca5(PO4)3Cl
pyromorphite Pb5(PO4)3Cl
vanadinite Pb5(VO4)3Cl
erythrite Co3(AsO4)2·8H2O
amblygonite LiAlPO4F
lazulite (Mg,Fe)Al2(PO4)2(OH)2
wavellite Al3(PO4)2(OH)3·5H2O
turquoise CuAl6(PO4)4(OH)8·5H2O
autunite Ca(UO2)2(PO4)2·10-12H2O
carnotite K2(UO2)2(VO4)2·3H2O
phosphophyllite Zn2(Fe,Mn)(PO4)2•4H2O
PO43- anion
DEPOSITS
• Rock phosphate can also be found on
USA, Egypt, Israel, Morocco, Navassa
Island, Tunisia, Togo, S. Arabia and
Jordan have large phosphate mining
industries as well.
USE OF PHOSPHATE
•
•
•
•
•
•
•
Phosphates were once commonly used in laundry detergent in the form trisodium
phosphate (TSP), but, because of algae boom-bust cycles tied to emission of phosphates
into watersheds, phosphate detergent sale or usage is restricted in some areas.
In agriculture, phosphate is one of the three primary plant nutrients, and it is a component
of fertilizers. Rock phosphate is quarried from phosphate beds in sedimentary rocks. In
former times, it was simply crushed and used as is, but the crude form is now used only in
organic farming. Normally, it is chemically treated to make superphosphate, triple
superphosphate, or ammonium phosphates, which have higher concentration of
phosphate and are also more soluble, therefore more quickly usable by plants.
Fertilizer grades have three numbers; the first is the available nitrogen, the second is the
available phosphate (expressed on a P2O5 basis), and the third is the available potash
(expressed on a K2O basis). Thus a 10-10-10 fertilizer would contain ten percent of each,
with the remainder being filler.
Surface runoff of phosphates from excessively-fertilized farmland can be a cause of
phosphate pollution, leading to eutrophication (nutrient enrichment), algal bloom, and
consequent oxygen deficit. This can lead to anoxia for fish and other aquatic organisms in
the same manner as phosphate-based detergents.
Phosphate compounds are occasionally added to the public drinking water supply to
counter plumbosolvency.
The food industry uses phosphates to perform several different functions. For example, in
meat products, it solubilizes the protein. This improves its water-holding ability and
increases its moistness and succulence. In baked products, such as cookies and crackers,
phosphate compounds can act as part of the leavening system when it reacts with an
alkalai, usually sodium bicarbonate (baking soda).
Phosphate minerals are often used for control of rust and prevention of corrosion on
ferrous materials, applied with electrochemical conversion coatings
PHOSPHATE FLOTATION
•
•
•
•
•
•
•
Collophane, the principal phosphate mineral occuring in the phospate
deposits of the Southeastern US, floats readily with crude fatty acids
and soaps, fuel oil and soda ash, caustic soda or amonia.
“Double flotation” method is used in US Florida plants by using both
fatty acid and amine types of collectors.
“Single flotation” is employed at N.Africa and Middle Eastern
phosphate operations by using either a fatty acid or an amine type of
collector.
Cytec’s Aero 727, 727J and 728 promoters have been successfully
used where only fatty acid float approach is practiced.
Cytec’s Aero 8651 fatty amine promer is utilized in operations running
an amine float.
In the reverse flotation, Cytec Acco-Phos 950 depressant (20-100 g/t)
minimizes phosphate loses into the silica froth product using amine
collectors.
In the treatment of sedimentary pebble phosphates, Aero 845 can be
used in conjuction with fatty acids.
US DOUBLE PHOSPHATE FLOTATION
-
FEED
Slimes (-10 )
Desliming
(Hydrocyclones)
+
conditioner
PhosphateSilica Sep. Flot
70%S
F
T
Silica (final tails)
Rougher fl.
pH=9-9.5
C
(sodaash/NaOH)
Conditioning with
Crude fatty oil
Silica Removal Reverse
Flot.
H2SO4+washing
Fuel-oil
to remove reagents
pH=6.5-7
Fatty/ether amine
Cleaner fl.
Phosphate
Conc.
conditioner
Silica (gangue)
LIME STONE/CALCITE
• Limestone is a sedimentary rock
composed largely of the mineral
calcite (calcium carbonate: CaCO3).
l
• Limestone often contains variable
amounts of silica in the form of
chert or flint, as well as varying
amounts of clay, silt and sand as
disseminations, nodules, or layers
within the rock.
USES OF LIMESTONE
Iron impregnations in limestone
• The manufacture of quicklime (calcium oxide) and slaked lime
(calcium hydroxide);
• Cement and mortar;
• Pulverized limestone is used as a soil conditioner to neutralize
acidic soil conditions;
• Crushed for use as aggregate—the solid base for many roads;
• Limestone is especially popular in architecture as building stone/
material;
• Geological formations of limestone are among the best petroleum
reservoirs;
• As a reagent in desulfurizations;
• Glass making;
• Toothpaste;
• Added to bread as a source of calcium
LIME STONE/CALCITE
(CaCO3) FLOTATION
•
•
•
•
•
•
•
Natural limestone/calcite deposits contain various types of silicates
and graphite impurities.
For applications like paper fillers the calcite has to have a low grade of
abrasive silicates as well as a high brightness.
Even very low amounts of graphite is detrimental to the brightness.
Beneficiation of limestone by froth flotation utilizing Aero 845
promoter can be simple process.
Limestone is floated with/without prior desliming with the emulsion of
Aero 845 and number 5 fuel oil.
Silicates can be depressed by Na2SiO3 (500-1000 g/t).
Compared to fatty acids, Aero 845 promoter (Pet. Sulphonate type
anionic collector) offer the advantage of better product control at a
saving in total collector usage.
Sparingly soluble salts flot.
Complete flot.
100
R=100%
recovery, %
80
pH:6- 9
60
fluorite
calcite
apatite
40
20
R=0%
No flot.
0
10
-06
10
-05
10
-04
10
-03
3
sodium oleate concentration, mol/dm
Mole/l
Calcite flot. recovery depends on NaOl concentration and HC chain
length of the collector. In general, when the collector length of the HC
chain is increased, the concentration of collector necessary for
flotation is reduced.
GRAPHITE CONCENTRATION
TECHNOLOGY
• Graphite is one of the allotropes of carbon.
Unlike diamond, graphite is an electrical
conductor.
• Graphite holds the distinction of being the
most stable form of solid carbon ever
discovered.
• It may be considered the highest grade of
coal, just above anthracite and alternatively
called meta-anthracite, although it is not
normally used as fuel because it is hard to
ignite.
CLASSIFICATION OF GRAPHITE
• There are three principal types of natural graphite, each
occurring in different types of ore deposit:
• (1) Crystalline flake graphite (53%) occurs as isolated,
flat, plate-like particles with hexagonal edges if unbroken
and when broken the edges can be irregular or angular
(Madagascar-open pit, 410-950 $/t)
• (2) Amorphous graphite occurs as fine particles (MexicoUnderground mines, 240-260 $/t)
• (3) Lump graphite (also called vein graphite) occurs in
fissure veins or fractures and appears as massive platy
intergrowths of fibrous or acicular crystalline aggregates,
and is probably hydrothermal in origin (Sri LankaUnderground mines).
USE AREAS OF GRAPHITE
MAJOR USE AREAS
REFRACTORIES
(High temperature applicationsMelting Point 3927°C)
Coarse flakes
Graphite crucibles
Carbon-magnesite/alumina bricks (95-99% C)
Monolitics (gunning and ramming mixtures)
Continuous casting ware (nozzles, troughs)
STEEL MAKING
Amorphous or fine flaked
Carbon rising in molten steel
Lubricating dies during hot metal extrution
EXPANDED GRAPHITE
Flakes
Made from flake graphite using chromic acid
sulphuric acids to produce foils
Can be used to insulate molten metal in
ladle, fuel cells and heat sinks for laptop
computer
MINOR USE AREAS
BRIKE LINING/SHOES FOR HEAVY
TRUCKS
FOUNDRY FACING and LUBRICANTS
PENCIL LEAD
Zn-C BATTERIES
ELECTRIC MOTOR BRUSHES
GRAPHITE(CARBON) FIBERS/NANOTUBES
Made from amourphous or fine flakes
Substitute for asbestos
Amourphous or fine flakes are used
High temp. dry lubricant
Powder graphite+clay
Powdered fine flaked graphite
Powder graphite
Reinforced/antistatic/conductive plastics/
concreates/rubbers
IMPURITIES and PROPERTIES
• Minerals associated with graphite include quartz,
calcite, micas, iron meteorites, and tourmalines.
• In 2005, world natural graphite production was
1.05 million t and China was the top producer of
graphite with about 80% world share followed by
India and Brazil.
• Graphite has various characteristics. Thin flakes
are flexible but inelastic, the mineral can leave
black marks on hands and paper, it is
diamagnetic, adsorbant, conducts electricity, and
displays superlubricity. Its best field indicators
are softness, luster, density and streak.
GRAPHITE BENEFICIATION METHODS
• Vary from a complex flotation at Europe and USA mills to
simply hand sorting and screening with/without milling of
high-grade ores in Sri Lanka.
• Certain soft flake-type graphite ores, (like in Madagascar) need
no primary crushing and grinding.
• GRAPHITE MILLING ONLY
•
Graphite can be ground to a fine powder for use as a slurry in oil drilling;
in zirconium silicate, sodium silicate and isopropyl alcohol coatings for
foundry molds; and for calcined petroleum coke, which is used as a
carbon raiser in the steel industry.
•
Rough graphite is typically ground and packaged at a graphite mill. Since
the Work Index of graphite is high, power consumption during grinding
will be high.
•
Environmental impacts from graphite mills consist of air pollution
including fine particulate exposure of workers and also soil contamination
from powder spillages leading to heavy metals contaminations of soil.
Dust masks are normally worn by workers during the production process
to avoid worker exposure to the fine airborne graphite and zircon silicate.
GRAPHITE FLOTATION
• Since graphite is naturally hydrophobic (i.e. floats easily),
impurites can easily be removed by direct flotation process.
•
•
•
•
•
•
Flotation process can be applied to low carbon and high silica
containing graphite ores.
1. DESLIMING STEP for removing clay minerals,
2. ROUGHER FLOTATION to produce a concentrate with 60-70% C.
3. REGRINDING+CLEANER FLOTATION to reach 85% C.
4. SCREENING to produce 75-95%C.
- 0.5 mm graphite can be floated using fuel-oil/kerosene as the
promoter and pine-oil/F-77/MIBC as frother at natural pH. Na2SiO3/HF
can be used as silicate depressant.
IRON ORES
Brazillian hematite
• Iron ores are rocks and minerals from which
metallic iron can be economically extracted. The
ores are usually rich in iron oxides and vary in
color from dark grey to rusty red. The iron itself
is usually found in the form of magnetite (Fe3O4),
hematite (Fe2O3), limonite or siderite. Hematite
ores containing 66% Fe can be fed directly into
iron making blast furnaces. Iron ore is the raw
material used to make pig iron, which is one of
the main raw materials to make steel. 98% of the
mined iron ore is used to make steel.
Consumption and economics
• Iron is the world's most commonly used metal. It is used primarily in
structural engineering applications, automobiles, and general
industrial applications (machinery).
• Iron-rich rocks are common worldwide, but ore-grade commercial
mining operations are dominated by few countries.
• World production averages one billion metric tons of raw ore
annually. The world's largest producer of iron ore is the Brazilian
mining corporation CVRD, followed by Australian company BHP
Billiton and the Anglo-Australian Rio Tinto Group.
• China, Japan and S. Korea are currently the largest consumer of
iron ore/steel. which translates to be the world's largest steel
producing country.
LOW GRADE IRON ORE
BENEFICIATION
• Due to the high density of hematite (5.3)
relative to silicates (2.7), beneficiation usually
involves a combination of crushing and
milling as well as heavy liquid separation.
• This is achieved by passing the finely crushed
ore over a bath of solution containing
bentonite or other agent which increases the
density of the solution. When the density of
the solution is properly calibrated, the
hematite will sink and the silicate mineral
fragments will float and can be removed.
FLOTATION OF IRON ORE
•
•
•
Due to increased demand for iron ore products low in silica and
phosphorous plus increased world competition, quality
considerations have become more and more important.
Dephosphorization of iron ores is necessary.
The results obtained in plant operations vary, depending on ore type
and the process.
•
Direct flotation of iron ores was practiced for many years using
Aero899R promoter (1-2 kg/t) along with number 5 fuel oil at pH 3-5
adjusted by H2SO4 following high solids conditioning.
•
Reverse flotation of silica with etheramine collectors+frother
(Aerofroth or Oreprep) has been the traditional route for many years to
produce a final iron ore concentrate. While removing silica from the
iron ore, fine iron particles should not excessively lost.
FINE IRON ORE PELLETS
Iron ore fines
and flotation
concentrates
should be
pelletized with
bentonite before
being charged
into the blast
furnace to
produce pig-iron
which is used in
steel production.
Iron pellets
HEAVY MINERAL SANDS
• Sand is a naturally occurring granular material
comprised of finely divided rock and mineral particles.
• Sand is transported by wind and water and deposited in
the form of beaches, dunes, sand spits, sand bars
(placer deposits) etc.
• The most common constituents of sands are silica
(SiO2), usually in the form of quartz, iron oxides, zircon,
rutile, ilmenite, monazite, garnet.
Heavy mineral sands are a class of ore deposit which is
an important source of zirconium, titanium, thorium,
tungsten, rare earth elements, the industrial minerals
diamond, sapphire, garnet, and occasionally precious
metals or gemstones.
Grade and Tonnage Distribution
•
•
•
•
•
•
•
•
•
The grade of a typical heavy mineral sand ore deposit is usually
low. The lowest cut-off grades of heavy minerals, as a total heavy
mineral (THM) concentrate from the bulk sand, in most ore
deposits of this type is around 1% heavy minerals, although
several are higher grade.
Of this total heavy mineral concentrate (THM), the components are
typically
Zircon, from 1% of THM to upwards of 50% of THM,
Ilmenite, generally of 10% to 60% of THM
Rutile, from 5% to 25% of THM
Black sand conc.
Leucoxene, from 1% to 10% of THM
Trash minerals, typically magnetite, garnet and chromite which
usually account for the remaining bulk of the THM content
Slimes, typically minerals as above and heavy clay minerals, too
fine to be economically extracted.
Modern open-pit mining practises tend to favor dry mining rather
than dredging operations, due to the advent of electrostatic
mineral separation processes.
USE OF SAND
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Sand is often a principal component of concrete.
Molding sand, also known as foundry sand, is moistened or oiled and then shaped into
molds for sand casting. This type of sand must be able to withstand high temperatures and
pressure, allow gases to escape, have a uniform, small grain size and be non-reactive with
metals.
It is the principal component in glass manufacturing.
Graded sand is used as an abrasive in sandblasting and is also used in media filters for
filtering water.
Brick manufacturing plants use sand as an additive with a mixture of clay and other
materials for manufacturing bricks.
Sand is sometimes mixed with paint to create a textured finish for walls and ceilings or a
non-slip floor surface.
Sandy soils are ideal for certain crops such as watermelons, peaches, and peanuts and are
often preferred for intensive dairy farming because of their excellent drainage
characteristics.
Sand is used in landscaping, it is added to make small hills and slopes (for example,
constructing golf courses).
Beach nourishment - transportation to popular beaches where seasonal tides or artificial
changes to the shoreline cause the original sand to flow out to sea.[2]
Sandbags are used for protection against floods and gun fire. They can be easily
transported when empty, then filled with local sand.
Sand castle building is a popular activity. There are competitive sand castle building
competitions (See sand art and play).
Sand animation is a type of performance art and a technique for creating animated films.
Aquaria are often lined with sand instead of gravel. This is a low cost alternative which
some believe is better than gravel.
Railroads use sand to improve the traction of wheels on the rails.
GLASS SANDS BENEFICIATION
•
•
CONCENTRATION OF HEAVY MINERALS
Gravity (sluices, spirals, shaking tables, Reichert cones), magnetic
(low/high intensity dry/wet) and high tension separation methods can
be used together to treat/upgrade the heavy content of the beach
sands.
•
•
GLASS SAND FLOTATION FOR IRON IMPURITY REMOVAL
After removal of the Fe-bearing impurities, some plants separate
feldspar from quartz by floating feldspar with amines at pH 3 using HF.
Some glass sand operations, naturally-occuring organic colloids may
make a fatty acid float of iron-bearing minerals preferable.
After desliming, the pulp is conditioned at high solids with Aero 700
series promoters at pH 8-9 adjusted with soda ash or caustic soda.
Fuel oil may be added to the flotation circuit for froth control.
•
•
crystal
Molecular
model
GARNET X3Y2(SiO4)3
• Garnet is a group of minerals that can be used as gemstones and
abrasives (Mohs hardness 6-7.5). Garnets are most often seen in
red, but are available in a wide variety of colors. Spec. Gr. is btw
3.1-4.3.
•
•
•
•
•
•
•
Major varieties
Pyrope
Almandine
Spessartite
Andradite
Grossular
Uvarovite
X Y (SiO4)3
Mg3Al2Si3O12
Fe3Al2Si3O12
Mn3Al2Si3O12
Ca3Fe2Si3O12
Ca3Al2Si3O12
Ca3Cr2Si3O12
USE AREA
abrasive
gemstone
gemstone
• Garnet species’s light transmission properties can range from the
gemstone-quality transparent specimens to the opaque varieties
used for industrial purposes as abrasives.
Uses & Concentration of GARNETS
Pure crystals of garnet are used as gemstones. Garnet
sand is a good abrasive, and a common replacement for
silica sand in sand blasting. Mixed with very high
pressure water, garnet is used to cut steel and other
materials in water jets. Garnet sand is also used for
water filtration media.
Garnets can be concentrated from sands by gravity+
electrostatic+magnetic separation methods along with
monazite.
Pendant in uvarovite, a rare bright-green garnet.
Almandine in gneissic rock,
hardness 6-7.5, abrasive
Spessartine (the yellow mineral)
gemstone
OCCURENCE OF KAOLIN
(Al2O3.2SiO2.2H2O)
•
•
• Granite
• Syanite
• Porphyr
•
•
•
Primary Deposits
Feldspar
Mica
alteration
20-30% Kaolin
Cormwall/UK
KAOLIN
Quartz
Rutile
Ilmenite
Sedimantary
Deposits
No-decomposition
95% Kaolin
Georgia/USA
LIBERATION OF KAOLIN
•
•
Liberation size for KAOLIN 4-6 m.
Liberation size for FELDSPAR 200-300 m.
•
Liberation size for QUARTZ 700 m.
• KAOLIN CAN EASILY BE CONCENTRATED BY
CLASSIFICATION ACCORDING TO PARTICLE SIZE USING
SCREENS AND HYDROCYCLONES
• Before concentration:
•  For soft kaolins→Attrition scrubbing for dispersing clays
•  For hard kaolins→crushing/grinding are required.
•
(Due to remaining fine silica product, quality is low)
• CLASSIFICATION CONCENTRATION
–  DRY (Crushing+dry grinding+air classification)
– (requires selective mining operation)
–  WET (Magnetic separation+flotation+hydrocyclones)
– (complex flowsheet, but product quality is very high)
• The production process includes:
disintegration and classification,
hydrocycloning, thickening, filterpressing and drying. Product range:
kaolin for ceramic, kaolin for paper,
glass silica sand, dry and wet classified
silica sand, ground kaolin, chamotte.
Process
•
•
•
•
•
The extraction plant is situated adjacent to the quarrying operation to enable the waste to
be returned to backfill.
Crude kaolin from the quarry is first made into a slurry with water. This slurry passes
through a series of washing and classification steps in order to remove the quartz and
mica impurities. This results in a pure kaolin product which is completely devoid of free
silica.
The kaolin is filtered in filter presses and the filter cake is pressed into pellet form prior to
drying in gas-fired dryers. The final kaolin pellets contain 10% moisture on average. These
are packaged and despatched to customers in the ceramic, paint, paper and other
industries.
A dry powder product is also produced for those industries that cannot tolerate moisture,
such as the rubber, plastic and pesticide industries. The dry powder is produced by
passing the kaolin pellets through an attritor and classifier with simultaneous drying with
hot air.
Water from the drying process is recovered and recycled to the extraction plant through a
return water pipeline.
MAJOR IMPURITIES
(Kaolin is used in fine size range. Flotation efficiency diminishes with the
size of particles. Kaolin is used as a white pigment thus colored
impurities must be removed).
• Anatase (TiO2): Fine sized anatase contains
considerable amount Fe and gives brownish tint to
the clays. This mineral may be removed by fatty acid
flotation after activating with divalent cations to
produce coating grade (bright) clays. Yoon et al.
(2003) found that alkyl hydroxametes were much
more effective than fatty acids in floating colored
anatase impurity from clays. No activation is
necessary and retention times in flotation are
shorter than fatty acids.
• Iron oxides
KAOLIN FLOTATION
• CARRIER FLOTATION and
CARRIERLESS FLOTATION can be
used.
• Collector: Fatty acids.
Sparingly Soluble Salts
100
SDS
recovery, %
80
DDA
60
fluorite
40
NaOl
20
0
2
4
6
8
10
12
14
pH
NaOl - sodium oleate, DDA-dodecylamine,
SDS,- sodium dedecyl sulfite
Class 5. Sparingly soluble salts
100
chrysocolla
recovery, %
80
calcite
60
40
bastnesite
20
barite
0
0
2
4
6
8
10
12
14
pH
Flotation with potassium octylohydroxymate
Class 4. Oxides and hydroxides
flotation recovery, %
100
80
QUARTZ
60
40
20
18
16 14
12
10
8
6
4
0 -08
-07
-06
-05
-04
-03
-02
-01
00
10 10 10 10 10 10 10 10
10
amine concentration, kmol/m 3
Amine flotation of quartz
Class 6. Soluble salts
flotation recovery, %
100
80
Na 2SO4×10H2O
KCl
K2SO4
60
40
20
0 -06
10
NaCl
Na 2SO4
-05
-04
-03
10
10
10
10
dodecylamine hydrochloride, kmol/m 3
-02
POTASH
• Potash is the most important source of potassium in
fertilizers.
• Flotation is one of the major methods to upgrade the
potash.
• Normally fatty acids are used as collectors for
flotation. However, this type of collectors is not
always suitable for the treatment of complex
phosphate ores when calcite and dolomite are
present.
• Calcite and dolomite tent to co-float with phosphate
giving low concentrate grades.
• Potash can be separated from halite by reverse
flotation.