Limestone;Industrial Uses of Limestone ; Lime; Lime Cycle; Production of Lime; Classification of Hydrated Lime IS 712-1973; Purposes for the Utilize of Lime; Soda Ash;Solvay process for the manufacture of Soda Ash; Purposes for the Utilize of Soda Ash; Gypsum; Calcination of Gypsum; Hardening of Plaster; Magnesium; Production Of Magnesium from seawater and dolomite; Process for production Magnesium hydroxide and Calcium chloride from Dolomite ; Process for production Magnesium and Calcium chloride

1. Lecture 3:
Beneficiation and Mineral Processing
of Calcium Carbonate and Calcium
Sulphate
Hassan Z. Harraz
hharraz2006@yahoo.com
Spring 2017
@ Hassan Harraz 2017
Beneficiation and Mineral Processing of Calcium Carbonate and Calcium Sulphate

2. OUTLİNE OF LECTURE 3:
Examples Mineral processing:
1) Limestone:
 Industrial Uses of Limestone
 Lime:
Lime Cycle
Production of Lime
Classification of Hydrated Lime IS 712-1973
Purposes for the Utilize of Lime
 Soda Ash:
 Solvay process for the manufacture of Soda Ash
 Monohydrate Process
 Purposes for the Utilize of Soda Ash
2) Gypsum
 Calcination of Gypsum
 Hardening of Plaster
 Uses
2

3. 1) CALCIUM CARBONATE DEPOSITS
 The solution, transportation, and deposition of calcium and magnesium
carbonate give rise to deposits of limestones and dolomite.
 The calcium is derived from the weathering of rocks and is transported to
the sedimentary basins chiefly as the bicarbonate, in part as carbonate
and as sulfate. Calcium carbonate (CaCO3) is deposited at all Eh
conditions but mostly at higher pH values, by organic and mechanical
means as well as by the photosynthesis of plants.
Ca2+ + CO3
2-  CaCO3
 Carbon dioxide plays a dominant role in inorganic processes because
the solution of the calcium carbonate in the sea is dependent upon it. If it
escapes, calcium carbonate is precipitated Organic deposition is
brought about by Algae, Bacteria, Morals, and Foraminifera. Entire
limestone beds may consist of Foraminifera or Nummulite shells, Coral,
or larger fragmental shell formed mainly in shallow waters. The
deposition has been brought about by chemical precipitation with
subsequent dehydration.
 Geological sources: Calcite, aragonite and vaterite are pure calcium
carbonate minerals. Industrially important source rocks which are
predominantly calcium carbonate include: limestone, chalk, marble and
travertine.
1.1) Introduction
3

4. Limestones are non-clastic rock formed either chemically or due to precipitation of calcite (CaCO3) from
organisms usually (shell) {Limestones are commonly containing abundant marine fossils}.
Limestones are the most common type of chemical sediment forming today by evaporation and biogenic
processing of seawater.
Limestones are of marine origin, and magnesium may in part replace the calcium, giving dolomitic
limestones even though dolomite is also of primary origin. Impurities of silica, clay, or sand are commonly
present, as well as minor amounts of phosphate, iron, manganese, and carbonaceous material.
Limestones formed by chemical precipitation are usually fine grained, whereas, in case of organic limestone the
grain size vary depending upon the type of organism responsible for the formation
 Chalk: which is made up of Foraminifera is very fine grained
 Fossiliferous Limestone: which medium to coarse grained, as it is formed out of cementation
of Shells.
 Coquina: larger fragmental shell formed mainly in shallow waters
 Limestone is an extremely common rock formed as shell beds on a shallow sea floor. Purity depends on the
environment of deposition and the subsequent mineralogical and tectonic history that may include
metamorphism to marble.
 These carbonate rocks or fossils, comprises primarily of Calcium Carbonate (CaCO3 ) or combinations of
Calcium (Ca) and Magnesium Carbonate (MgCO3) with varying amounts of impurities (silica and alumina)
 High quality deposits exist – 98% CaCO3 high purity grade…..But, impurities are always present: MgCO3,
Al2O3, Fe2O3, SiO2
 The relatively modest price even for the high-calcium and high-brightness grades of GCC (less than $200/t)
means that consumption is generally close to the point of production (i.e., a local or regional market).
 In Western Europe, chalk is important in the United Kingdom, France, and Belgium, whereas crushed marble
is often used in Italy and Greece.
1.2) Limestone
4

5. Calcium Carbonate Deposits
Non-fossiliferous Limestone Fossiliferous Limestone
Fossiliferous
Limestone
Non-fossiliferous
Limestone
Oolitic Limestone
Oolitic LS Dunes,
Bahamas
Biogenic
Inorganic, ~clastic
5

6. Chemical and biochemical sedimentary Calcium Carbonate
Limestones
Travertine Coquina
6

7.  Has many of the uses outlined for limestone, plus several others, including in refractories, in
seawater magnesia and magnesium metal production, and as a dimension stone.
 Although less common than limestone, dolomite production, particularly for aggregates, is
extremely widespread.
 Dolomite is created by replacement of calcium by magnesium after shallow burial of limestone.
Dolomite usually forms in tropical shallow marine environments.
 The main producers are Spain, the United Kingdom, Belgium, France, Germany, Norway,
Sweden, and Finland.
 In the EGYPT, nonaggregate production is concentrated in Ain Al Sukhna-Red Sea, Sinai, and
West Alexandria. Europe has an active dolomite industry where it is used extensively as a raw
material for refractories and seawater magnesia production.
1.2) Dolomite (or dolostone)
7

8. Why is limestone important?
1.3) Industrial Uses of Limestone
 Limestone is widely used as a Construction, Building Construction Material –
(Concrete, blocks…etc).
 Limestone is used to strengthen and stabilize the sub-grade in road construction.
 Limestone is an alkali and is used extensively to neutralize acids – pH control.
 Limestone, the source material for all lime based value added products – calcined.
 Calcined and Lime:
 Iron and steel the manufacture
 Water and effluent treatment.
 Chemical industry (e.g. Soda Ash), Gaseous effluent neutralization.
 Agriculture and food products.
 Manufacture - cement and glass
 Crushed: Glass making, Sugar refining, Flow gas desulphurization, Ceramics.
 Ground:
i) Fine to very fine fillers: Paper, Paint, Plastics, Adhesives, Sealants,
Pharmaceuticals, Food and Drinks
ii) Coarse to medium fillers: Agriculture, Carpet backing, Animal feeds, Asphalt
filler, Floor coverings and tiles.
 Paper, plastic, paint and rubber producers use calcium carbonate as a way to improve
quality and lower manufacturing costs.
8

9. Limestone mountains - Siwa Oasis
Limestone Deposits in Egyptian
• Egyptian’s most abundant
mineral is limestone 50 - 60
billion tonnes.
• High quality deposits exist – 98%
CaCO3 high purity grade.
9

10. 1.4) LIME
 Lime is one of man's oldest and most vital chemicals. The ancient Romans used lime in building and
road construction, uses which continue to the present day.
 Lime has always been a cheap commodity because limestone deposits are prevalent anywhere.
 Often the term ‘lime’ is used incorrectly to describe limestone products.
 This is a frequent cause of confusion.
 Lime is produced by burning calcium and/or magnesium carbonates at temperatures of between 900
and 1200°C. Furthermore, temperatures of up to 1800°C can be possible, e.g. for achieving sintering
(e.g. Dead Burned Lime). These temperatures are sufficiently high in order to liberate carbon dioxide
and to obtain the derived oxide.
 Lime Products:
 Quicklime, (or so-called ‘Burned Lime)’, is calcium oxide (CaO) produced by the decarbonization
of limestone (CaCO3).
 Slaked lime (or Hydrated lime)
is produced by reacting or ‘slaking’ quicklime with sufficient water to form a dry, white powder
that consists mainly of calcium hydroxide (Ca(OH)2).
includes hydrated lime (dry calcium hydroxide powder), milk of lime and lime putty
(dispersions of calcium hydroxide particles in water).
 However, 90 % of the total amount produced is lime and 10 % dolime.
 A distinction is made between calcium limes, dolomitic limes and hydraulic limes.
 Calcium limes are by far the largest category and are supplied in lump, ground and hydrated
forms.
 Dolomitic limes are more specialized products and are supplied in smaller quantities in lump,
ground, hydrated and dead burned forms.
 Hydraulic limes are partially hydrated and contain cementitious compounds, and are used
exclusively in building and construction.
10

11. 1.4.1) Production/ Manufacture
Vertical Lime Kiln
1.4) LIME
Excavation
Crushing Limestone
Grinding
Calcination → Quicklime/ Calcined lime
Pulverize quicklime
Hydration: Mix with water under pressure → Slaked Lime
Drying of Slaked Lime
Pulverizing
Marketing in bags.
11

12. 1.4.2) Lime Cycle
12

13. 1.4.1) Calcination of Limestone
 Lime is produced by burning calcium and/or magnesium carbonates at temperatures of between 900 and
1200°C (i.e., Quicklime/Calcined lime /Burnt lime).
CaCO3  heat (>900° to 1200oC)  CaO + CO2
“Quick lime”
ΔH1200-1300ºC = 4GJ/t of lime produced
 Furthermore, temperatures of up to 1800°C can be possible, e.g. for achieving sintering (e.g. Dead
Burned Dolime). These temperatures are sufficiently high in order to liberate carbon dioxide and to
obtain the derived oxide.
 Therefore, the process depends on an adequate firing temperature of at least more than 800°C in order
to ensure decarbonization and a good residence time, i.e. ensuring that the lime/limestone is held for
a sufficiently long period at temperatures of 1000 –1200°C to control its reactivity.
 The reactivity of quicklime is a measure of the rate at which the quicklime reacts in the presence of water.
The test method to measure the reactivity of ground lime by slaking the lime in water is described in the
European standard EN 459-2. To measure the reactivity of lump lime, some other methods are used in
the lime industry, such as the so-called ‘Wuhrer-Test’.
 The reactivity of lime depends on different parameters related to the raw material and the process. These
parameters are:
 Burning temperature and time
 Crystalline structure of the limestone
 Impurities of the Limestone
 Kiln type and fuel.
 The classification of Lime is often seen in terms of its reactivity, such as: dead burned, hard, medium,
and soft.
13

14. Flow diagram of the cornerstones for lime manufacturing
14

15. General principles of lime calcination
Continuous Kiln
15

16. Table 1: Lime nomenclatures, EC and CAS numbers
Chemical compound Chemical
formula
Synonyms EC # CAS #
Calcium oxide CaO
Lime, burned lime and
quicklime
215 – 138-9 1 305 – 78-8
Calcium magnesium
oxide
CaO MgO Dolomitic lime, dolime 253 – 425-0 37 247 – 91 – 9
Calcium hydroxide Ca(OH)2
Calcium hydrate, calcium
hydroxide, caustic lime,
hydrated lime and slaked
lime
215 – 137-3 1 305 – 62-0
Calcium magnesium
tetrahydoxide CaMg(OH)4
Dolomitic hydrated lime,
calcium magnesium
hydroxide
254 – 454-1 39 445 – 23-3
Source: [44, EuLA, 2006]
16

17. i) Quicklime (or Calcined lime /Burned Lime):
 It is a white, caustic, alkaline crystalline solid at room temperature.
 Dangerous form of lime.
 It is obtained by heating (Calcining) pure limestone (calcium
carbonate) at temperatures above 900oC in a Kiln.
This reaction takes place at 900°C (at which temperature the partial
pressure of CO2 is 1 atmosphere), but a temperature around 1000°C (at
which temperature the partial pressure of CO2 is 3.8 atmospheres) is
usually used to make the reaction proceed quickly.
Overburned (or Dead-burned) lime: Furthermore, temperatures of up to
1800°C can be possible, (e.g. for achieving sintering).  result from
changes in the calcium oxide itself, as well as from certain impurities acted
upon by excess heat, recognized as masses of relatively inert, semi-
vitrified material.
On the other hand, it is Underburned lime if it often happens that rather
pure limestone is calcined insufficiently and lumps of calcium carbonate are
left in the lime.
17

18. Classification of Quicklime /Calcined lime /Burned lime
A) According to Particle Size:
 Lump Lime (10-30 cm lumps)
 Pebble Lime (2-5 cm)
 Granular Lime (~0.5 cm)
 Crushed Lime (~5-8 mm)
 Ground Lime (passes #10 sieve, by grinding crushed lime)
 Pulverized Lime (passes #100 sieve)
B) According to Chemical Composition:
 High-Calcium Quicklimes (~90% CaO)
 Calcium Quicklime (75% CaO)
 Magnesian Quicklime ( > 20% of MgO)
 Dolomitic Quicklime ( > 25% of MgO)
C) According to Intended Use:
 Mortar Lime
 Plaster Lime
18

19. ii) Hydration Process
 Hydrated Lime (Calcium Hydroxide) is produced either by adding water to
burned quicklime in a Hydrator or by absorbing moisture from the air.
 The quicklime is then – thoroughly mixed with excess amount of water to produce
lime putty/ Lime water / Milky lime (calcium hydroxide), or with
less water to produce dry Slaked Lime / dry hydrated lime.
 The slaking process involved in creating a slaked lime or lime putty is an
exothermic vigorous reaction which initially creates a liquid of a cream consistency.
 Slaked Lime is a dry calcium hydroxide powder, resulting from the controlled
slaking of Calcined quicklime with less water and under the specific technical
parameters of moisture in a Hydrator.
 Factors affecting heat evolution and rate of slaking:
 Quicklime particle size
 Chemical composition
 acid insoluble
 Burning temperature
CaO + H2O  Ca(OH)2 + Heat (i.e. exothermic)
ΔH = -66.5 kJ
Expansion observed
19

20. Classification of Hydrated Lime IS 712-1973
Class Commercial Lime Type Uses
Class- A:
Eminently Hydraulic
Lime
Can be used for structural works such as
arches domes ..etc.
Class- B: Semi-Hydraulic Lime Can be used for constructing masonry
Class- C: Fat Lime
Can be used for Finishing Coat in
Plastering, white washing, …etc. or
used for masonry mortar with addition of
pozzolanic material
Class- D:
Magnesium / Dolomite
Lime
Can be used for Finishing Coat in
Plastering and white washing.
Class- E: Kankar Lime
Can be used for masonry mortar (Produce
by burning Lime Nodules).
Class- F: Siliceous dolomite Lime
Can be used generally for undercoat and
finishing coat of plaster
Note That
Hydraulic lime:
 Is a Slaked lime, used to make lime mortar (paste used to bind construction blocks together and fill the
gaps between them)
 It Obtained from burning of limestone containing clay and other impurities
Hydraulicity is the ability of lime to set under water or wet conditions
20

21. 21

22. 22

23. Precipitated Calcium Carbonate (PCC)
Ca (OH)2 + CO2 → CaCO3  + H2O
 Carbonation of Hydrated lime, also known as purified, refined or
synthetic Calcium carbonate.
 Pure calcium carbonate (e.g. for food or pharmaceutical use), can be
produced from a pure quarried source (usually marble).
 Whiting – pure, finely divided CaCO3 prepared by wet grinding and
levigating natural chalk.
 Putty – produced when whiting is mixed with 18% boiled linseed oil
Air-Slaked Lime
 At surface of uncovered quicklime (CaO)  it picks up moisture
and CO2 from air  becomes partly CaCO3.
air
23

24. 1.4.3) Dolomitic Lime
The decomposition of dolomites and magnesium/dolomitic limestone is
much more complex.
Decomposition can occur via a single or two discrete stages or even via
intermediate stages:
CaCO3 • MgCO3 + heat  CaCO3 • MgO + CO2 
184 g 140 g 44 g
CaCO3 • MgO + heat  CaO • MgO + CO2 
140 g 96 g 44 g
CaCO3 • MgCO3 + heat  CaO • MgO + 2CO2 
184 g 96 g 88 g
The temperature required for the decomposition of dolomites and
magnesium/dolomitic limestone is usually in the range of 500 –750°C.
24

25. 1.4.4) Purposes for the Utilize of Lime
Industrial water / wastewater treatment. Water Purifications: All Water purifying treatment
plants.
Metallurgy : Steel Manufacture, Steel Products Manufacture, Magnesium Manufacture,
Alumina Manufacture, Ore Flotation and Non-Ferrous Metal Smelting.
Pulp And Paper : Sulfate Process, Sulfite Process, Bleaching, Precipitated Calcium
Carbonate, Strawboard Manufacture, and in the treatment of pulp and paper mill liquid wastes,
as a coagulant in color removal.
Chemicals : Alkalis, Calcium Carbide and Cyanamid, Petrochemicals, Bleaches, Dye and
Dyestuff Intermediates and Coke- By-Products. In addition, it is used in the purification of citric
acid, glucose and dextrin; metallic calcium; soda-lime, an adsorbent; and for countless other
minor or isolated purposes, such as for CO, absorption.
MAJOR USES of LIME
Flux – Alumina, Steel
Lubricant – Wire drawings, Oil Wells
Neutralization –Water Treatment, Agricultural soils
Solvent – Leather, Paints
Absorption – Bleaches, Sulphur Dioxide removal
Raw Material – Rubber, Cement, Concrete, Glass, Tooth-paste
Bonding Agent – Mortars, Plasters, Road & Soil stabilization
Causticization – Caustic soda, Alkali scrubbing
25

26.  Water Treatment : Scope, Softening, Purification, Coagulation, Neutralization of Acid Water, Silica Removal
and Removal of Other Impurities.
 Sewage Treatment : Maintain proper pH and Stabilizing Sewage Sludge
 Industrial Trade Wastes : Treatment of industrial trade wastes to abate pollution from Steel and Metal
Fabricating Plants, Chemical and Explosives Plants, Acid Mine Drainage, Paper and Fibers, Food Plants
and in clarifying "water gas" acid waste effluents.
 Flue Gas Desulfurization,
 Solid Wastes Disposal
 Building Materials industry: Calcium Silicate Brick, Concrete Products, Miscellaneous Building Units, and
Insulation Materials.
 Protective Coatings : Pigments, Water Paints, and Varnish.
 Food & Food By Products : Dairy Industry, Sugar Industry, Animal Glue and Gelatin Industries, Baking
Industry, and CA (controlled atmospheric) Storage of Fresh Fruit and Vegetables. All tortillas are made with
lime treatment.
 Miscellaneous Uses : Petroleum, Leather, and Rubber.
Environmental Uses of Lime
26

27. Why Use Lime?
1) Lime Allows Buildings To Breathe In the search by architects and conservators for building materials sympathetic to
traditional construction, lime was found to be one of the most important. One of the reasons lime binders are promoted by the
Society for the Protection of Ancient Buildings for repairs is because they are vapour permeable and allow buildings to
breathe. This reduces the risk of trapped moisture and consequent damage to the building fabric
2) Lime Provides A Comfortable Environment Porous and open textured materials such as lime plasters, help to stabilize the
internal humidity of a building by absorbing and releasing moisture. This makes for a more comfortable environment and
reduces surface condensation and mould growth.
3) The Use Of Lime Has Ecological Benefits • Lime has less embodied energy than cement. • Free lime absorbs carbon
dioxide in the setting process of carbonation. • It is possible to produce lime on a small scale. • The gentle binding properties
of lime enable full re-use of other materials. • A very low proportion of quicklime will stabilize clay soils. • Small quantities of
lime can protect otherwise vulnerable, very low energy materials such as earth construction and straw bales.
4) Lime Binds Gently With Early Adhesion The fine particle size of lime, far smaller than cement, is linked to the root meaning of
the word lime, which is 'sticky material'. Due to the fine particle size, lime mixes penetrate minute voids in the background
more deeply than other materials. They bind gently and the stickiness gives good adhesion to other surfaces.
5) Lime Mortar Can Protect Adjacent Materials Lime mortars with a high free lime content are porous and permeable. These
characteristics allow lime mortars to protect adjacent materials by handling moisture movements through the building fabric
and protecting them from harmful salts. Adjacent materials frequently affected this way include timber and iron as well as
stone and brick masonry.
6) Lime Renders Can Assist Drying Out By Evaporation Dense and impermeable renders can trap moisture within the building
fabric. Trapped moisture is often the agent for various decay mechanisms. Dense renders used in conjunction with softer
materials or on weaker backgrounds can cause serious problems by creating local stresses. High calcium lime renders allow
evaporation and reduce the risk of trapped moisture and decay. In simple terms, the greater the extent of pure lime and
permeability the better this is for the building. This needs to be balanced with durability, however, and some reduction in
permeability may be necessary to obtain adequate weathering qualities, hence the advantage of feebly hydraulic limes for
external use.
7) Lime Mixes Have Good Workability The ability of a mortar or plaster to remain smooth and mouldable, even against the
suction it may experience from porous building materials, is termed workability. Good workability greatly assists good
workmanship, helping to achieve full joints with good bonding to the other materials. This is what makes lime based mixes
such a pleasure to use. The workability provided by the lime allows the inclusion of widely graded and sharp aggregates in
the mix. These enhance both the performance and the aesthetic of the finished work.
27

28. Table 2.1: Lime, a versatile material –some industrial applications
Application sectors Application details
Environment –gas
used to neutralise flue-gas pollutants such as sulphur and chlorine blended with additives, it captures heavy
metals
Environment –water
effluent treatment –treatment of industrial and mining waste water (pH adjustment, removal of phosphorus
and nitrogen, and water clarification) potable water softening and removal of impurities from drinking water
waste water treatment
Environment –waste treatment of medical and hazardous waste treatment of organic and inorganic sludges
Environment –
contaminated lands
adjustment of pH and immobilisation of sulphates, phosphates and heavy metals
Construction and civil
work
used in the production of bricks and structured block masonry and plaster mixes for building facades
soil stabilisation and lime road binders
Agriculture soil treatment –to adjust the pH of soils to give optimum growing conditions and hence improve crop yields
Steel and non-ferrous
metals
used in steelmaking processes in order to reduce sulphur and phosphorus, to modify slag viscosity, to protect
refractories and to form the slag
used as a flux in the smelting of copper, lead, zinc and other metals from their ores
used to neutralise and coat wire after it is cleaned with acid
Chemical and paper
industry
paper –manufacturing process; pulp and raw material for precipitated calcium carbonate (PCC)
oil additive for lubricants (such as sulphonates, phenates and salicylates) plastics –used as a desiccant in the
manufacture of petrochemical based products
used in leather tanning
used in the glass and soda industries acid neutralisation
Pharmaceutical,
personal care and food
use in the matrix composition of drugs
used in the manufacture of calcium phosphate, a toothpaste additive used in the manufacture of food and
drink additives
used in the sugar industry to precipitate out impurities from beet and cane extracts and also to neutralise
odours generated by beet washing and transport
Source: [44, EuLA, 2006]
28

29. 1.5) SODA ASH
Forms of Soda Ash
 Soda ash is the trade name for sodium carbonate (Na2CO3),
a chemical refined from the mineral trona or from sodium
carbonate-bearing brines (both referred to as natural soda
ash) and manufactured from one of several chemical
processes (referred to as synthetic soda ash).
 It is an essential raw material in glass, chemicals, detergents,
and other important industrial products.
 Anhydrous sodium carbonate (NaHCO3)
 Texture: soft
 Color: grayish & white
 Appearance: lump / powder in nature
 Natural Form:
 Nahcolite (NaHCO3)
 Trona (NaHCO3.Na2CO3.2H2O)
 Natron (Na2CO2.10H2O)
Soda Ash (NaHCO3)
Manufactured
synthetically through
Solvary process and
Monohydrate process.
29

30. i) Solvay process for the manufacture of Soda Ash (NaHCO3)
cwx.prenhall.com/petrucci/medialib/ media_portfolio/22.html
Soda Ash (NaHCO3) Manufactured synthetically through Solvary
process by using salt, ammonia & limestone
30

31. ii) Monohydrate Process for the manufacture of Soda Ash (NaHCO3)
 The monohydrate method is the primary process used to make soda ash.
 In the monohydrate process, trona (NaHCO3.Na2CO3.2H2O) is crushed and
calcined in rotary gas-fired calciners operating at 150-300°C.
 Calcining removes water and carbon dioxide from the ore, leaving an impure
product containing 85 percent soda ash and 15% insolubles.
 The calcinate is dissolved with hot water and sent to evaporative, multiple-
effective crystallizers or mechanical vapor recompression crystallizers where
sodium carbonate monohydrate crystals precipitate at 40-100°C.
 This is below the transition temperature of monohydrate to anhydrous soda
ash. The insoluble portion of the ore containing the shale and shortite are
collected by clarifiers, filtered, and washed to recover any additional alkali
before they are piped as a slurry to a tailing pond or injected underground.
 Some companies pass the liquor through activated carbon beds prior to
crystallization to remove trace organics solubilized from the oil shale so
organics do not interfere with the crystal growth rate.
 The crystals are sent from the crystallizers to hydroclones and dewatering in
centrifuges.
 The centrifuge cake is conveyed to steam tube dryers where the crystals are
dehydrated into anhydrous soda ash at 150°C, screened, and sent to
storage or shipment.
 The final product made by the monohydrate process is dense soda ash
31

32. Soda Ash Monohydrate Process Flow Diagram
32

33. 1.5.3) Purposes for the Utilize of Soda Ash
History:
 Early Egypt: make glass & soap
 Early Roman: make glass, bread &
pharmaceuticals (medicine) purpose to
cure choric & skin rashes
 Food
 Glass manufacture (49%)
 Chemical production (27%)
 Pulp & Paper manufacturing
 Sodium compounds
manufacturing
 Soap & detergents (11%)
 Water treatment (2%)
 Textile processing
 Cleaning preparations
 Petroleum refining
 Metallurgical refining
(Mineral processing in
mining)
 Metal refining
 Removal of sulfur from
smokestack emissions (3%)
(5%)
Nowaday:
33

34. 2) GYPSUM
 very soft sulfate mineral composed of calcium sulfate,
CaSO4·2H2O
 If the heating is at a higher temperature, gypsum loses
all its water and becomes anhydrous calcium sulfate,
anhydrite (CaSO4).
 Calcined gypsum (the half water salt) can be made
into wall plaster by addition of a filler material (eg.
asbestos, wood pulp or sand).
 Plaster of paris (without addition) can be used for
making sculptures and craft projects.
2.1) INTRODUCTION
34

35. ‫فورماشان‬ ‫دباب‬ ‫ابو‬
(Anhydrite and Gypsum)
Gypsum Quarry in Eastern
Desert
35

36. 2.2) Calcination of Gypsum
 Grinding the mineral and placing it in large calciners holding 9 to 22 tons.
 Temperature is raised to 120 to 150ºC, with constant agitation to maintain
uniform temperature.
 The material in the kettle, plaster of paris or first-settle plaster, may be
withdrawn and sold at this point, or it can heated further to 190ºC to make a
second-settle plaster
CaSO4·2H2O  CaSO4· ½H2O + 1½H2O
ΔH25ºC = +69 kJ
 First-settle plaster is approximately the half hydrate, CaSO4· ½H2O
 Second-settle plaster is anhydrous
 Practically all gypsum plaster sold in the form of first-settle plaster mixed with
sand or pulp.
 Second form is used in manufacture of plasterboard and other gypsum
products.
 Gypsum may be calcined in rotary kilns similar to those used for limestone.
36

37. 2.3) Hardening of Plaster
Hydration chemical conversion:
CaSO4· ½H2O + 1½H2O  CaSO4· 2H2O
ΔH = - 2.9 kJ
Plaster sets and hardens because the liquid
water reacts to form a solid crystalline hydrate.
Hydration with liquid water takes place at
temperature below about 99ºC and thus
gypsum must be heated above 99ºC for
practical dehydration.
37

38. 2.4) Uses
Gypsum is used in a wide variety of applications:
Gypsum board is primarily used as a finish for walls and ceilings, and is
known in construction as drywall, sheetrock or plasterboard.
 component of Portland cement used to prevent the flash settling
of concrete.
added about 4- 5% during the final grinding
Gypsum blocks used like cement blocks in building construction.
Gypsum mortar is an ancient mortar used in building construction
Plaster ingredient (surgical splints, casting moulds, modeling)
Plaster of Paris: heated form of gypsum used for casts, plasterboard, …
etc.
A binder in fast-dry tennis court clay
Adding hardness to water used for brewing
Used in baking as a dough conditioner, reducing stickiness, and as a
baked-goods source of dietary calcium. The primary component of mineral
yeast food.
A component of Portland cement used to prevent flash setting of concrete
Soil/water potential monitoring (soil moisture)
Impression plasters in dentistry.
Used in mushroom cultivation to stop grains from clumping together.
38

39. Follow me on Social Media
http://facebook.com/hzharraz
http://www.slideshare.net/hzharraz
https://www.linkedin.com/in/hassan-harraz-3172b235
39