aspects of industrial chemical processes:
products, type of process flowsheet, mass balance, energy balances, heat transfer and heat exchangers, reactor design and operation, separation and purification processes, process instrumentation and process control, materials handling, process economics, safety and environmental issues, quality
industrial chemical processes:
chemical processes are used to produced chemical products and the processes which include chemical transformations
specific products produced by the chemical industry and pharmaceutical industry include: aspirin, ibuprofen, paracetamol, naproxen, labetalol, etc.
these active pharmaceutical ingredients (api) are produced by chemical reactions
route(material, steps, operations, etc.)
“recipe”(material, quantities, etc.)
plant equipment(operations)
process operating conditions
basic info:
many chemicals are mixed with other chemicals to produce formulations suitable for consumer use. these are paint, fragrances, pesticides, and medicinal products.
ex: ibuprofen is the api in the over the counter (otc) product “nurofen”.
dose
particle size
flow properties
bulk density
some processes are used to develop specific chemicals, ex: contact process for making sulfuric acid
a chemical can be produced in more than one way
different sectors ( or product groups), each with their own characteristics. ex: pharmaceuticals, pesticides, fertilizers, petrochemicals, dyestuffs etc.
type of chemical produced determines the particular characteristics of the process used to produce the products. ex: ammonia, aspirin
classification of chemical products
bulk chemicals, large volume production, supported by market demand, lower unit costs ex: sulfuric acid
fine chemicals, relatively smaller scale, more versatile, batch operations, unit cost higher, used as ingredients in formulations, intermediates in the production of more complex chemicals ex: “ibuprofen” (bulk pharmaceuticals)
specialty chemicals, manufactured from basic chemicals used by industry and domestic consumers for specific purposes, ex: adhesives, coatings, pharmaceutical, disinfectants
output: product, by-products, co-products, spent catalyst, solvents, waste, energy, etc
chemical process operations:
batch/semi-batch
continuous
process dynamics
steady state
unsteady state
advantage of feedback control system:
accurate error correction: continuously monitors and rectifies output deviation
stability: maintaining accuracy and balancing variation in input or disturbances
adaptability: adjust to disturbances and variations, ensures consistency
simplified design: feedback loops can be implemented without much predictive modeling
broad applicability
advantages of feed forward control systems:
faster response: preempts before an error takes place
simple design: no feedback loop simplifies the system design
efficient for predictable systems: good for systems that go through abrupt disruptions
smooth operation: maintains stability by adjusting inputs early
prevents disturbances:
mass balance:
rate of accumulation = rate of mass in - rate of mass out
chemical reaction(s) carried out in a chemical reactor is called chemical processes
multi purpose/ product plant for bulk api
batch reactors
material feed system to reactors
separation and purification equipment
material storage
waste treatment
emissions control
equipment
batch reactors
filter driers crystallisers
double cone vacuum driers
mixers and granulators fluid bed driers
centrifuges
cyclone separators
separation processes
a sequence of separation processes used in the production of bulk pharmaceutical products is: crystallization, filtration or centrifugation and drying
factors in separation processes
quantity of material to be separated
rate of separation required
feasibility
selectivity
economics
quality
equipment
mode of operation
utilities
steam
colling water
chilled water
other heat transfer fluids
inert gases
compressed air
electricity
demineralized water
utility process water
distilled water
specs of purified water/ water for injection (wfi)
obtained from potable water
specified in pharmacopoeias
storage
depth filter
organic trap
carbon filter
DI
filtration (0.45 micro)/ UV (245 nm)
UF (0.22 micron)
distillation
material storage
reactant
product
intermediates
solvents
catalyst
reagents
flowsheet
used to describe the operating details of chemical processes
schematic representation
arrangement of equipment
interconnection
movement of material stream connections
stream flows
stream compositions
operating conditions
types of flowsheets
flowcharts (block)
process flow sheets (process flow diagram)
piping and instrumentation diagram (PID)
simple flowcharts are used to show the main material being routed through different processes
flowcharts are the graphical representation of the data or algorithm for better understanding
PFD is a flowchart that illustrate relationships between major components at an industrial plant
used to document, to improve and to model a process
sulfuric acid
history
oldest industrial applied processes. discovered by a Persian alchemist in the tenth century
saltpeter(potassium nitrate) and sulfur were mixed in a glass container and burned in a moist atmosphere, then the acid was collected from the condensed vapors.
In England, 1746, the lead chamber reactor was invented that made production rates higher(<78%)
Also in England, 1831, a patent was filed that described the oxidation of sulfur dioxide over a platinum catalyst, the Contact Process. This new process increased yields of reaction from 70% to above 95%.
In 1913, BASF was granted the a patent for the use of V2O5 , in 30s, it dominated because of its low cost and insensitivity to poisons.
In 1960, a patent application was filed by Bayer using the so-called double-catalyst process (double absorption).
oxidation of sulfur S+O2→SO2
primary generation of SO2 :
79% combustion of sulfur
9% recovery from metallurgic processes
5% regeneration of spent acids
process:
airdrying tower with acid
sulfur is injected into a burner
reaction temperature 2000^degree^ F (1100^degree^ C)
Exothermic reaction must be cooled
Steam recovered
chlor-alkali
major products
soda ash(Sodium Carbonate)
caustic soda(Sodium Hydroxide)
Chlorine
one of the most important heavy chemical industries, and the applications are vast and diverse such as: soap and detergent, fiber and plastic, glass, petrochemicals, pulp and paper, fertilizers, explosives, solvents, and various other chemicals
chlor-alkali industry in India
the chlor-alkali industry in India is around 60 years old, it started with a few thousand ton per annum and now it is 2.24 million ton per annum
there are 41 production units:
32%(21) = obsolete mercury cell technology
68%(19) = latest membrane cell technology
SOLVAY AMMONIA-SODA PROCESS
Ernest Solvay, devised it in 1864
Raw Materials:
common salt
ammonia
limestone (for supplying CO2 and quicklime(CaO))
Merits:
higher purity (~99.5%)
less expensive and raw materials are cheap and CO2 and NH3 are recovered and used again
CaCl2 is the only waste and so no pollution problems
Formation of NaHCO3 is an intermediate
Plant location considerations:
1 ton of Na2CO3 requires 8 tons of brine, limestone and coal, so proximity to raw materials is a prime consideration. Salt sources are usually the key factor as they are less widely distributed that limestone/coal. In India, there are several plants located in Gujarat and in Tamil Nadu near solar salt evaporation stations, and in the Sambhar salt lake district of Rajasthan.
Principle of Solvay Process
2)CO_{2} + H_{2}O \rightarrow H_{2}CO_{3} \\
3)NH_{4}OH + H_{2}CO_{3} \rightarrow NH_{4}HCO_{3} \\
4)NH_{4}HCO_{3} + NaCl \rightarrow NaHCO_{3} + NH_{4}Cl
\end{gather*}$$
***Steps***
NaHCO~3~ is slightly soluble in water gets precipitated and it is removed by filtration and changed into sodium carbonate by heating
$$2NaHCO_{3} + Ca(OH)_{2} \rightarrow Na_{2}CO_{3} + H_{2}O + CO_{2}$$
The mother liquor remaining after the precipitation of NaHCO~3~ contains NH~4~Cl which is used to regenerate ammonia(raw material) by steam heating with milk of lime(Ca(OH)2).
$$2NH_{4}Cl + Ca(OH)_{2} \rightarrow CaCl_{2} + 2H_{2}O + 2NH_{3}$$
lime is obtained by heating limestone
$$CaCO_{3} \rightarrow CaO + CO_{2}$$
ammonia and carbon dioxide liberated are utilized in making the whole process cyclic and continuous.
***Components of a Solvay Plant - 1***
- ***Saturating or ammoniating tank***: In this tank, impurities of calcium and magnesium salts present in the brine are precipitated as carbonates or hydroxides. This occurs when a little carbon dioxide gas (from ammonia recovery tower) is bubbled through a 20% sodium chloridesolution(brine).
- $$\begin{gather*}1)2NH_{3} + CO_{2} + H_{2}O \rightarrow NH_{4}CO_{3} \\ 2)CaCl_{2} + (NH_{4})_{2}CO_{3} \rightarrow CaCO_{3} + 2NH_{4}Cl\\ 3) MgCl_{2} + 2NH_{4}OH \rightarrow Mg(OH)_{2} + 2NH_{4}Cl\\ 4) MgCl_{2} + (NH_{4})_{2}CO_{3} \rightarrow MgCO_{3} + 2NH_{4}Cl \end{gather*}$$
Ammonia absorption tower fitted at the top of the saturating tank absorbs the ammonia that escapes absorption in the saturating tank
- ***Carbonating tower***: carbonation of ammoniacal brine is carried out on the principle of counter-current. The clear ammoniacal brine solution is pumped to the top of the tower. This flows downwards and meets a current of CO~2~ introduced from the bottom of the tower at a pressure of 1-2 atmosphere. As a result of the reaction therein, (NH~4~)Cl and crystals of NaHCO~3~ are formed
- $$\begin{gather*}1)NH_{3} + CO_{2} + H_{2}O \rightarrow NH_{4}HCO_{3} \\ 2)2NH_{3} + H_{2}O + CO_{2} \rightarrow (NH_{4})_{2}CO_{3} \\ 3)(NH_{4})_{2}CO_{3} + H_{2}O + CO_{2} \rightarrow 2NH_{4}CO_{3} \\ NH_{4}HCO_{3} + NaCl \rightarrow NaHCO_{3} + NH_{4}Cl\end{gather*}$$
- ***Rotary suction filter:*** This thick milky liquid is then filtered by means of the rotary suction filter. NaHCO~3~ deposits on the filter cloth. After washing with a spray of cold water it is scrapped off, and dried. The filtrate containing (NH~4~)~2~CO~3~, NH~4~Cl and some NaCl is pumped to the top of the ammonia recovery tower.
- ***Lime Kiln:*** Here, limestone is burnt to produce carbon dioxide and lime. $$\begin{gather*}CaCO_{3} \rightarrow CaO + CO_{2}\end{gather*}$$
- Carbon dioxide is sent to the carbonating tower, while the lime is slaked in a large quantity of water to form milk of lime. This is pumped to middle of the ammonia recovery tower.
- ***Ammonia recovery tower:*** The filtrate from the rotary suction filter containing NH~4~HCO~3~ and NH~4~Cl is introduced at the top of the tower. Milk of lime enters at the middle part, and steam is introduc3ed from the base. NH~4~HCO~3~ is decomposed by the heat while NH~4~CL is decomposed by milk of lime. $$\begin{gather} 1)NH_{4}HCO_{3} \rightarrow NH_{3} + H_{2}O + CO_{2} \\ 2)2NH_{4}CL + Ca(OH)_{2} \rightarrow CaCl_{2} + 2H_{2}O + 2NH_{3} \end{gather}$$
The gaseous ammonia along with a little carbon dioxide is sent to the saturation tank, while the liquid flowing out of the tower contains calcium chloride, which is a useful by-product.
- ***Calcination:*** NH~4~HCO~3~ obtained from the rotary suction filter is calcined in closed tubular calcining pans fitted with scrapers. On calcination, Na~2~CO~3~ is formed and CO~2~ is evolved. $$2NaHCO_{3} \rightarrow Na_{2}CO_{3} + H_{2}O + CO_{2}$$
The soda ash obtained from the pans is dissolved in water and crystals of hydrated Na~2~CO~3~.10H~2~O, are recovered from the solution by crystallization.
- ***Chlor-Alkali Process for NaOH:***
- A chlor-Alkali process always implies the electrolysis of common salt or NaCl
- Depending on the method several products beside hydrogen can be produced.
- If the products are separated, Cl~2~ and NaOH are the products;
- By mixing, sodium hypochlorite Na(OCl)~2~ or sodium chlorite NaOCl~2~ are produced, depending on the temperature.
- High temperature are needed for production of sodium chlorite NaOCl~2~ instead of sodium hypochlorite Na(OCl)~2~. Industrial scale production began in 1892.
- Using calcium chloride (CaCl~2~) and potassium chloride (KCl), the products contain calcium or potassium instead of sodium.
- The process has a high energy consumption and produces equal (molar) amounts of chlorine and sodium hydroxide
- ***Manufacturing Process For NaOH:***
- 3 production methods in use:
- membrane cell
- diaphragm cell
- mercury cell
- While the mercury cell method produces Cl~2~ free NaOH. The use of several tons of mercury leads to extremely serious environmental problems, although in normal production cycle the emission of mercury is relatively low, but a few hundred pounds of mercury per year released to the environment.
- The Cl~2~ and NaOH via mercury-cell chlor-alkali process are themselves contaminated with trace amounts of mercury. The membrane and diaphragm method use no mercury, but the NaOH contains Cl~2~ which needs to be removed.
- ***Membrane Cell Process:***
- Saturated brine is passed into the first chamber of the cell where the chloride ions are oxidized at the anode to chlorine $$2Cl^- \rightarrow Cl_{2} + 2e^-$$
- At the cathode, hydrogen in the water is reduced to hydrogen gas (H~2~), releasing OH^-^ in the solution.$$2H_{2}O + 2e^- \rightarrow H_{2} + 2OH^-$$
- The non-permeable ion exchange membrane at the center of the cell allows the sodium ions (Na^+^) to pass to the second chamber where they react with the OH^-^ ions to produce caustic soda(NaOH). The overall reaction for the electrolysis of brine is thus: $$2NaCl + 2H_{2}O \rightarrow Cl_{2} + H_{2} + 2NaOH$$
- A membrane cell is used to prevent the reaction between the Cl~2~ and OH^-^. If this reaction occurs, the chlorine will be disproportionated to form chloride and hypochlorite ions:$$Cl_{2} + 2OH^- \rightarrow Cl^- + ClO^- + H_{2}O$$
- At higher temperatures, 333K, ++chlorate++ can be formed:$$3Cl_{2} + 6OH^- \rightarrow 5Cl^- ClO_{3}^- +3H_{2}O$$
- Because of the corrosive nature of the chlorine produced, the anode has to be made from a non-reactive metal such as titanium, whereas the cathode can be made from steel.
- In the membrane cell, the anode and cathode are separated by an ion-permeable membrane, the saturated brine is fed to the first compartment with the anode ( the anolyte). A DC current is passed through the cell and the NaCl splits into its constituent components. The membrane passes Na^+^ ions to the cathode compartment (catholyte), where it forms NaOH is solution. The chloride ions are oxidized to chlorine gas at the anode, which is collected, purified and stored. Hydrogen gas and Hydroxide ions are formed at the cathode.
- ***Diaphragm Cell Process:***
- Diaphragm cell contain a diaphragm, usually made of asbestos fibers, to separate the anode from the cathode. This allows ions to pass through by electrical migration but reduces the diffusion of products. Anode have usually been made of graphite, cathode of cast iron. The diaphragms become clogged with use, as indicated by higher voltage drop and higher hydrostatic pressure on the brine feed. The diaphragm permits a flow of brine from anode to cathode and thus greatly lessens or prevents side reactions.
- ***Mercury Cell Process:***
- Mercury cells operate quite differently from the other types. The anodes remain either graphite or modified titanium. but the cathode is a flowing pool of mercury. The electrolysis produces a Hg-Na alloy (amalgam) which is not decomposed by the brine present.
- In the mercury-cell process, mercury, which flows along the bottom of the electrolytic cell, serves as the cathode. When an electric current passes through the brine, chlorine is produced at the anode and sodium dissolves in the mercury, forming Na-Hg amalgam. The amalgam is them poured into a separate vessel, where it decomposes into sodium and mercury. The sodium reacts with water in the vessel, producing the purest caustic soda, while the mercury returns to the electrolytic cell.
- | **Aspect** | **Membrane Cell** | **Diaphragm Cell** |
|---------------------------|------------------------------------------------------|----------------------------------------------|
| **Separation Method** | Uses porous, chemically active plastic membrane | Uses diaphragm separator |
| **Ion Selectivity** | Allows Na⁺ ions; rejects OH⁻ and Cl⁻ ions | Less selective; allows more ion mixing |
| **Product Purity** | Produces purer NaOH (lower salt content) | Produces less pure NaOH (higher salt content)|
| **NaOH Concentration** | 25%–40% NaOH directly | Lower concentration NaOH |
| **Evaporation Requirement** | Only ~715 kg water evaporated to reach 50% NaOH | Requires more evaporation |
| **Operational Advantage** | Can operate near point of use → saves transport cost | Less flexible in operation location |
| **Brine Requirement** | Requires more concentrated brine | Uses less concentrated brine |
| **Maintenance Issue** | Membranes clog easily (Ca²⁺, Mg²⁺ must be removed) | Less prone to clogging |
| **Product Quality** | Higher purity, concentrated output | Lower purity output |
- ***Chlorine - Beneficial Impact:***
- More than 90% of European drinking water is made safe with the help of chlorine, which disinfects right up to the tap.
- Chlorine plays a key role in controlling diseases such as typhoid, cholera and diarrhea - particularly in lesser-developed regions of the world
- There is still a great need for chlorinated drinking water as globally up to 2,000,000 children continue to die each year of diarrhea cause by waterborne microbes.
- PVC plastic is made with chlorine, used in 25% of medical devices. These include blood bags, sterile tubing, heart catheters and prosthetics.
- 85% of medicines, including many life-saving drugs, are synthesized using chlorine chemistry.
- Chlorine is used in household bleach, disinfectants and antiseptics to combat a wide range of microbes in homes, hospitals, swimming pools, restaurants and other public places.
- Chlorine decontaminates public water supplies damaged by natural disasters, such as hurricanes, floods, tornadoes and earthquakes.
- Protective equipment used by the police, fire and ambulance services is made with materials dependent on chlorine. Ex: bullet-resistant vests, face shields and helmets.
- Communication equipment and components used by emergency services are also made with chlorine-based materials. Ex: radios, mobile, telephones and microprocessors.
- Chlorine chemistry is used in home construction for PVC window frames and pipes, concrete, insulation, adhesives, paints, carpets
- Consumer products that depend on chlorine chemistry include toiletries and cosmetics, contact lenses, computers, televisions and compact discs.
- About 96% of crop protection chemicals used to boost yields and quality are based on chlorine chemistry.
- Many leisure activities rely on equipment made using chlorine: soccer balls, tents, waterproof clothing, skateboards, tennis rackets and skis.
- Automotive components using chlorine include upholstery, bumpers and mats, dashboards, fan and alternator belts, hoses, gaskets and seals.
- ***Bleaching powder:***
- Bleaching powder(calcium oxychloride) is made by the reaction:$$Ca(OH)_{2} + Cl_{2} \rightarrow Ca(OCl)Cl + H_{2}O $$
- This reaction is carried out below 50 degree C in a countercurrent fashion by passing Cl~2~ through a rotating steel cylinder with inner lifting blades which shower the solid through the path of the gas.
- ***Calcium Hypochlorite:***
- Made in several ways:
- Chlorination of calcium hydroxide, followed by the separation of the Ca(OCl)~2~ through salting out from solution with NaCl.
- Chlorination of mixture of sodium and calcium hydroxides to form the salt Ca(OCl)~2~.NaOCl.NaCl.12H~2~O under refrigeration. This is reacted with a chlorinated lime slurry, filtered to remove salt, and dried, resulting finally in a stable product containing 65 to 75% Ca(OCl)~2~.
- The advantage of Ca(OCl)~2~ is that it does not decompose on standing as does bleaching powder, and it is twice as strong as ordinary bleaching powder and is not hygroscopic.
- It is employed as a disinfectant and deodorant in dairies, creameries, water supplies, sewage disposal, and for household purposes. It is also used as a b leach in laundries.
- As a bleaching agent it is very useful for cotton, linen, jute, rayon, paper, pulp, and oranges.
- The most common method for making it is the treatment of NaOH solution with gaseous Chlorine.$$2NaOH + Cl_{2} \rightarrow NaCl + H_{2}O + NaOCl$$
- ***Sodium Chlorite Impacts:***
- It is manufactured from chlorine through calcium chlorate to chlorine dioxide, end with the reaction: $$4NaOH + Ca(OH)_{2} + C 4ClO_{2} \rightarrow 4NaClO_{2} + CaCO_{3} + 3H_{2}O$$
- After filtering off the calcium carbonate, the solution of NaClO~2~ is a powerful but stable oxidizing agent.
- It is capable of bleaching much of the coloration in cellulosic materials without weakening the cellulose fibers.
- It finds uses in the pulp and textile industries, particularly in the final whitening of kraft paper.
# fertilizers
***history of nitrogen production:***
- 1774, J. Priestly and C. Berthollet using ammonium carbonate
- by the 1840's, additional ammonia was recovered from coke oven plants and gas works as a by-product of the destructive distillation of coal
- early 1900, American Cyanamid(company), produced Ca(CN)<sub>2</sub> from CaC<sub>2</sub> and N<sub>2</sub>
- about 1900, haber began investigating ammonia equilibrium reaction and evaluating effect of temperature.
- in 1908, BASF and haber -> industrial-scale production plant
- working with bosch's group within basf in 5 years the process was developed
***history of nitric acid production:***
- nitric acid occurs in nature in the form of nitrate salts. large scale production of nitric acid began with sodium nitrate as feedstock
- beginning of 20th century, sodium nitrate low
- nitric acid was needed for explosives, munitions (weapons), and developing dyestuffs business
- 3 techniques:
- production of NO, by reaction N<sub>2</sub> and O<sub>2</sub> at greater > 2000degree C, abandoned because poor energy efficiency
- hydrolysis of calcium cyanamide, not widely accepted
- production of ammonia from N<sub>2</sub> and H<sub>2</sub>.
# soil nutrients
- macro: required by the plant in relatively large amount
- micro: required in small amounts
- non-mineral elements: carbon, hydrogen, oxygen
- primary nutrients: nitrogen, phosphorus, potassium
- secondary nutrients: calcium, magnesium, sulfur
micro nutrients:
- iron
- copper
- zinc
- boron
- molybdenum
- manganese
- chlorine
***functions of nitrogen***
- promotes growth of leaves and stems
- gives dark green color and improves quality of foliage
- necessary to develop cell protein and chlorophyll
- deficiency:
- sick, yellow-green color
- short stems, small leaves, pale colored leaves and flowers
- slow and dwarfed plant growth
***functions of phosphorus***
- stimulates early formation and growth of roots
- provides fast and vigorous growth and speeds maturity
- stimulates flowering and seed development
- necessary for the enzyme action of many plant processes
- deficiency:
- decrease in growth
- slow in maturity
- older leaves are purplish color
***functions of potassium***
- used to form carbohydrates and proteins
- formation and transfer of starches, sugars and oils
- increases disease resistance, vigor and hardness
- deficiency:
- mottled (different colors without a regular pattern)
- spotted, streaked or curled leaves
- scorched, burned, dead leaf tips and margins
***functions of calcium***
- improves plant vigor
- influences intake and synthesis of other plant nutrients
- important part of cell wall
- deficiency:
- small developing leaves
- wrinkled older leaves
- dead stem tips
***functions of magnesium***
- influences the intake of other essential nutrients
- helps making fats
- assists in translocation of phosphorus
- deficiency:
- interveinal chlorosis-yellowing of leaves between green veins
- leaf tips curl or cup upward
- slender, weak stalks
***functions of sulfur***
- promotes root growth and vigorous vegetative growth
- essential to protein formation
- deficiency:
- young leaves are light green with lighter color veins
- yellow leaves and stunted growth
***functions of iron***
- essential for chlorophyll production
- helps carry electrons to mix oxygen with other elements
- deficiency:
- mottled and interveinal chlorosis in young leaves
- stunted growth and slender, short terms
***functions of copper***
- helps in the use of iron
- helps respiration
- deficiency:
- young leaves are small and permanently wilt
- multiple buds at stem tip
***functions of zinc***
- plant metabolism
- helps forming hormones
- reproduction
- deficiency:
- retarded growth between nodes (rosetted)
- new leaves are thick and small
- spotted between veins, discolored veins
***functions of boron:***
- affects water absorption by roots
- translocation of sugars
- deficiency:
- short, thick stem tips
- young leaves of terminal buds are light green at base
- leaves become twisted and die
***functions of manganese***
- plant metabolism
- nitrogen transformation
- deficiency symptoms:
- interveinal chlorosis
- young leave die
***functions of molybdenum***
- plant development
- reproduction
- deficiency:
- stunted growth
- yellow leaves, upward curling leaves, leaf margins burn
***functions of chlorine***
- essential to some plant processes
- acts in enzyme systems
- deficiency:
- usually more problems with too much chlorine than deficiency
# nitric acid
***History of Ammonia Production:***
- **1774:** Free ammonia first prepared by J. Priestley and C. Berthollet using ammonium carbonate.
- **1840s:** Additional ammonia recovered as a by-product from coke oven plants and gas works (destructive distillation of coal).
- **Early 1900s:** American Cyanamid (pharma company) formed; produced calcium cyanamide (nitrolime) from calcium carbide (CaC₂) and nitrogen (N₂) at 1000°C.
- **~1900:** Fritz Haber began studying ammonia equilibrium and temperature effects (synthesis from elements).
- **1908:** BASF and Haber agreed to develop industrial-scale ammonia production.
- **Next 5 years:** Process fully developed with Karl Bosch’s group at BASF.
- **1913:** First commercial plant started in Ludwigshafen, Germany (30 tons/day).
- Nitric acid occurs naturally as **nitrate salts**; early large-scale production used **sodium nitrate** as feedstock.
- Early 20th century: sodium nitrate reserves declined → processes developed to **replace nitrate with nitrogen**.
- Demand driven by **explosives, munitions (military weapons), and dyestuffs industry**.
- Three industrial techniques:
- Production of nitric oxide (NO) by reacting N~2~ and O~2~ at greater > 2000°C, abandoned due to **poor energy efficiency**.
- Production of ammonia by hydrolysis of calcium cyanamide, not widely accepted.
- Production of ammonia from N~2~ and H~2~. (Haber-Bosch Process) $$ \mathrm{N_2 + 3H_2 \xrightleftharpoons[ ]{Fe} 2NH_3}$$
***Reaction Steps:***
a. CH₄(g) + CO₂(g) ⇌ 2CO(g) + 2H₂(g)
b. CH₄(g) + H₂O(g) ⇌ CO(g) + 3H₂(g)
c. CH₄(g) + ½O₂(g) ⇌ CO(g) + 2H₂(g)
d. CH₄(g) + 2O₂(g) ⇌ CO₂(g) + 2H₂O(g)
e. CH₄(g) ⇌ C(s) + 2H₂(g)
f. 2CO(g) ⇌ C(s) + CO₂(g)
g. CO₂(g) + H₂(g) ⇌ CO(g) + H₂O(g)
h. C(s) + H₂O(g) ⇌ CO(g) + H₂(g)
i. C(s) + O₂(g) ⇌ CO₂(g)
n. 5CH₄(g) + 7/2 O₂(g) → 9H₂(g) + 4CO(g) + CO₂(g) + H₂O(g)
***Observed Reaction Steps:***
I. CH₄(g) + 5/8 O₂(g) ⇌ CO(g) + 7/4 H₂(g) + 1/4 H₂O(g)
II. CH₄(g) → C(s) + 2H₂(g) *(Methane cracking)*
III. 2CO(g) → C(s) + CO₂(g) *(Boudouard reaction)*
IV. CO₂(g) + H₂(g) → CO(g) + H₂O(g) *(Reverse water-gas shift reaction)*
***Production of Nitric Acid from NH~3~***
- The critical step in nitric acid production and the catalytic combustion of ammonia was developed by Ostwald around the turn of the century and was in production by 1906.
- The Ostwald Process:
- Catalytic Combustion:$$\mathrm{4NH_{3} + 5O_{2} \rightarrow 4NO + 6H_{2}O }$$
- The combustion of ammonia is one of the most efficient catalytic reaction with possible conversion up to 98%.
- The catalyst is platinum, and the reaction occurs at 900°C. The catalyst is a Pt-Rh fine-mesh gauze, where the Rh provides strength.
- The biggest issue with this method is the loss of precious metal at reactor temperatures.
- Recovery gauze is typically used to absorb platinum oxide vapor and form an alloy. This gauze can periodically be removed to recover platinum.
- Oxidation of NO:$$\mathrm{2NO + O_{2} \rightarrow 2NO_{2} \xrightleftharpoons[]{} N_{2}O_{4}}$$
- The NO is cooled and route to the absorption tower and, if necessary, compressed.
- As a result of this process, part of the NO is oxidized to nitrogen dioxide(NO~2~) and dinitrogen tetroxide(N~2~O~4~)
- To describe the kinetics of NO oxidation, a third-order rate equation is used.
- This reaction is unusual because the reaction is quicker at lower temperatures. The reaction rate has a negative temperature coefficient.
- Absorption:$$\mathrm{3NO_{2} + H_{2}O \rightarrow 2HNO_{3} + NO}$$
- Finally, the gas is sent to an absorption tower, where it is cross-exchanged with water.
- The reaction model is quite complicated because of the number of components reacting (NO, NO~2~, N~2~O~3~, N~2~O~4~, etc.)
- The absorption tower is governed by the calculations for the oxidation process. Oxidation proceeds more slowly as the NO~x~ concentration decreases at the top of the tower, therefore the spacing between the plates increases.
- Acid formation takes place mainly in the bottom third of the reactor whereas NO~x~ is reduced in the upper two-thirds.
- As as result, most of the heat of the reaction is withdrawn in the lower third of the tower.
- The coils on the upper plates work to keep the NO gas cool for fast reaction.
- ***Main Reaction:***$$\begin{gather}1)N_{2}O_{4} + H_{2}O \rightarrow HNO_{2} + HNO_{3} \\ 2)3HNO_{2} \rightarrow HNO_{3} + H_{2}O + 2NO\end{gather}$$
***Higher Concentrations of Nitric Acid:***
- Nitric acid can be concentrated to about 68% in water with the above-described process.
- This concentration is adequate for most fertilizer applications but not for chemical nitration reactions.
- However, there are ways to overcome the azeotrope (68% in water) and go to higher acid concentration
- ***Concentrated Acid Processes:***
- **Direct** - injecting or absorbing NO~x~ into weak nitric acid under pressure.
- **Indirect** - extractive distillation and rectification with sulfuric acid or magnesium
***Markets and Uses of Nitric Acid:***
- The largest use of nitric acid is in the fertilizer industry, with 74-78 percent
- The second largest use is for the manufacture of chemicals. Some examples are cyclohexanone, di-nitrotoluene, and nitrobenzene
- Finally, explosives, metal nitrates, nitrocellulose, nitro-chlorobenzene, a metal treatment solvent, rocket propellant, and nuclear fuel processing.
# cement
"A cement is a binder, a substance that sets and hardens and can bind other materials together. Its principal constituents for constructional purpose are compounds of Ca(calcareous) and Al + Si(argillaceous)"
***Chemical Composition of Cement:***
| Lime | 63% |
| ---------- | ------- |
| Silica | 22% |
| Alumina | 6% |
| Iron oxide | 3% |
| Gypsum | 1 to 4% |
- building material for binding bricks, stones or aggregates
- used for making mortar or concrete
- cements can be natural and artificial
- natural cement: burning and crushing of stones and lime
- artificial cement: burning at high temperature and gypsum is added
***Raw Materials Necessary for Portland Cement Manufacturing:***
- **Calcium (Lime):** Excess ↓ strength; deficiency → quick setting
- **Silica:** Higher silica ↑ strength but ↑ setting time
- **Alumina:** Causes quick setting; excess weakens cement
- **Iron (Iron oxide):** Provides hardness and strength
- **Magnesia:** Contributes to hardness and color
***Types of Cements:***
- **Natural Cement**
- **Pozzolanic Cement** :
- mixtures of Portland cement and a pozzolanic material that maybe natural or artificial
- natural pozzolanas are mainly materials of volcanic origin but include some diatomaceous earths
- used artificial materials include fly ash, burned clays and shales.
- Pozzolanas are materials that, though not cementitious in themselves, contain silica (and alumina) in a reactive form able to combine with lime in the presence of water to form compounds with cementitious properties
- **Slag Cement** :
- granulated slag made by the rapid chilling of suitable molten slags from blast furnaces forms the basis of this cement
- mixture of Portland cement and granulated slag, containing up-to 65% slag, is known as Portland blast-furnace (slag) cement.
- Properties of these slag cements are broadly similar to those of Portland cement but they have a lower lime content and higher silica and alumina content.
- **Portland Cement**:
- variety of artificial cement
- name comes from rocks near Portland, England resembling its color
***Portland Cement:***
- A hydraulic cement (cement that not only hardens by reacting with water but also forms a water-resistant product) produced by pulverizing (crushing into fine powder) clinkers consisting essentially of hydraulic calcium silicates, usually containing one or more of the forms of calcium sulfate as an inter ground addition.
- Clinkers are nodules (diameters of 5-25mm) of a sintered material that is produced when a raw mixture of predetermined composition is heated to high temperature
***Raw Materials of Portland Cement & Their Use:***
- **Calcareous Materials (CaO)** : eg: Limestone
- Principal constituent; proportion can be regulated
- Excess lime ↓ strength; causes expansion & disintegration
- Too little lime ↓ strength due to quick setting
- **Argillaceous Materials (Al₂O₃, SiO₂)** — e.g., Clay
- Imparts strength
- Causes quick setting
- Excess alumina weaken cement
- **Powdered Coal / Fuel Oil:**
- Used for burning
- **Gypsum (CaSO~4~.2H~2~O):**
- Retards and controls quick setting
***Manufacturing of Cement:***
- Mixing and Crushing of raw materials
- Dry process
- Wet process
- Burning
- Grinding
- Storage and Packing
***Manufacturing of Portland Cement (Flow Process)***
- **Raw Material Preparation**
- **Argillaceous + Calcareous materials**
- If **wet process**:
- Washing → Basin → Grinding (+ water) → Slurry → Correcting basin → (A)
- If **dry process**:
- Crushing & Grinding → Silos → (A)
- **Burning & Clinker Formation**
- (A) → **Rotary Kiln** (+ powdered coal + air)
- Formation of **hot clinkers**
- **Cooling**
- **Final Processing**
- Grinding in **ball mill** (+ 2–4% gypsum)
- **Storage silos**
- **Packing**
***Clinker & Gypsum in Portland Cement***
- Clinker
- Formed by burning **calcium _ siliceous raw materials** in a kiln
- Typical size ≈ **20 mm diameter**
- Gypsum
- Source of **sulfate**
- Interground with clinker to form **Portland cement**
- Functions:
- Controls **settings**
- Reduces **drying shrinkage**
- Improves **strength development**
***Grinding:***
- Clinker is ground with gypsum (calcium sulfate) to produce Portland cement
- Fine grinding is necessary for high early strength
- 85-95% -325(45 microns)
- ~ 7 trillion particles per pound
- Gypsum absorb water and prevents setting of C~3~A during shipment
***Clinker Phases:***
- Alite or 3CaO.SiO~2~ or C~3~S
- Hydrates & hardens quickly
- High early strength
- Higher heat of hydration (setting)
- Belite or 2CaO.SiO~2~ or C~2~S
- Hydrates & hardens slower than alite
- Gives off less heat
- High late strength (> 7 days)
- Modern cements are manufactured to be higher in alite for early strength
- Aluminate or 3CaO.Al~2~O~3~ or C~3~A
- Very high heat of hydration
- Some contribution to early strength
- Low C~3~A for sulfate resistance
- Ferrite or 4CaO.Al~2~O~3~.Fe~2~O~3~ or C~4~AF
- Little contribution to strength
- Lower clinkering temperature
- Control the color of cement
***Types of Portland Cement:***
- Normal
- Moderate sulfate resistance
- High early strength
- Low heat of hydration
- High sulfate resistance
***Sulfate Attack:***
The main reactions of sulfate attack on concrete are as follows:
- Formation of **sulfoaluminate** (ettringite) by reaction of sulfate salts and the C~3~A phase present in the cement $$\begin{gather}C_{3}A + 3CSH_{2} + 26H \rightarrow C_{3}A(CS)_{3}H_{32}\end{gather}$$
Increase volume of reaction products cause expansion and spalling
- Formation of calcium sulfate (gypsum) in the reaction with lime (CH) formed by hydration of cement $$\begin{gather}NS + CH + 2H \rightarrow NH + CSH_{2}\end{gather}$$
Increase volume of reaction products cause expansion and spalling
- Magnesium sulfate is more aggressive than sodium or calcium salts. There are some other reactions also.
***Chloride Attack:***
- Chloride attack is one of the most important aspects while dealing with durability of concrete. It primarily causes corrosion of reinforcement. Statistics have indicated that over 40% of failure of structures is due to the corrosion of steel.
***Concrete and Passive Layer:***
- The strongly alkaline nature of Ca(OH)~2~ (pH ~ 13) prevents the corrosion of the steel by the formation of a thin protective film of iron oxide on the metal surface. This protection is know as passivity.
- If the concrete is permeable to such an extend that soluble chloride penetrate right up to the reinforcement where water & oxygen is also present, then the corrosion of steel will take place. This layer can also be lost due to carbonation.
***Oxides & Abbreviations***
- **CaO** → C
- **SiO₂** → S
- **Al₂O₃** → A
- **Fe₂O₃** → F
- **MgO** → M
- **SO₃** → S̅
- **H₂O** → H
***Compounds & Abbreviations:***
- **3CaO·SiO₂** → C₃S
- **2CaO·SiO₂** → C₂S
- **3CaO·Al₂O₃** → C₃A
- **4CaO·Al₂O₃·Fe₂O₃** → C₄AF
- **4CaO·2Al₂O₃·SO₃** → C₄A₂S̅
- **3CaO·2SiO₂·3H₂O** → C₃S₂H₃
- **CaSO₄·2H₂O** → CSH₂
> **C₃S:** Tricalcium silicate
> **C₂S:** Dicalcium silicate
***Manufacture of Portland Cement:***
- **Limestone (CaCO₃) + Clay** (or similar composition)
- Heating to ~**1450°C**
- **Partial fusion** → **Clinker** *(~67% C, 22% S, 5% A, 3% F + 3% others)*
- Grinding + mixing with **~6% gypsum (CaSO₄·2H₂O)**
- **Portland cement**
***Main Phases of PC Clinker***
1. **C₃S**
2. **C₂S**
3. **C₃A**
4. **C₄AF**
***Types of Portland Cement (ASTM Classification)***
1. **Type I — Ordinary Portland Cement**
- **Composition (%):**
- C₃S: 42–65
- C₂S: 10–30
- C₃A: 0–17
- C₄AF: 6–18
- **Characteristics:**
- No special requirements
2. **Type II — Modified Portland Cement**
- **Composition (%):**
- C₃S: 35–60
- C₂S: 15–35
- C₃A: 0–8
- C₄AF: 6–18
- **Characteristics:**
- Moderate sulfate resistance
- Moderate heat of hydration
3. Type III — High Early Strength Portland Cement
- **Composition (%):**
- C₃S: 45–70
- C₂S: 10–30
- C₃A: 0–15
- C₄AF: 6–18
- **Characteristics:**
- High strength soon after pouring
4. Type IV — Low Heat Portland Cement
- **Composition (%):**
- C₃S: 20–30
- C₂S: 50–55
- C₃A: 3–6
- C₄AF: 8–15
- **Characteristics:**
- Low heat of hydration
5. Type V — Sulfate Resistant Portland Cement
- **Composition (%):**
- C₃S: 40–60
- C₂S: 15–40
- C₃A: 0–5
- C₄AF: 10–18
- **Characteristics:**
- High sulfate resistance
***Mechanism of Cementing Action:***
1. **C₃S, C₃A**
- React rapidly with water
- Strongly hydraulic
2. **β-C₂S**
- Reacts slowly with water
- Strongly hydraulic
- **γ-C₂S** is inert
3. **C₃A, C₄AF**
- React rapidly with water
- Weakly hydraulic
***Explanation:***
- Many compounds are stable at room temperature when **Ca atoms are coordinated to six oxygen atoms**.
- At high temperature, compounds have **coordination number < 6**
- Reactivity arises from Ca’s tendency to **attain coordination number 6**
- **Irregular arrangement** of coordinated oxygen also contributes to reactivity
- Presence of **minor impurities** may also increase reactivity
***Theories of Setting and Hardening:***
- Crystallization Hypothesis (by Le Chatelier)
- Cement + H₂O → solution (supersaturated w.r.t. hydration products)
- → Precipitation of hydration products as **crystals**
- Crystals interlock → **hardened mass**
- Gel Hypothesis (by Michaelis)
- Hardening due to **gel formation**
- Gel is soft and contains much water
- Unreacted cement particles absorb water from gel for hydration
- Gel becomes **hard and impermeable**
***Modern Views of Setting & Hardening:***
- **Cement + H₂O** → dispersion system (cement grains not closely packed)
- Large amount of **hydration products (colloidal size)** form on grain surfaces
- After a few hours:
- Hydration increases and products extend to meet each other
- Gel forms in spaces between grains → **setting stage**
- After a few days:
- Colloidal particles become **densely packed** → hardened material
- Gel becomes unevenly packed → formation of **pores** → **hardening stage**
***Hydration of Portland Cement:***
- **Solution Mechanism**
- Reactants dissolve → form ions in solution
- Ions combine → form products
- Products precipitate from solution
- **Topochemical Mechanism**
- Reaction occurs directly on the **solid surface**
***Hydration Reaction:***
1. **Hydration of C₃S:**
$$2C_3S + 6H \rightarrow C_3S_2H_3 + 3Ca(OH)_2 $$
2. **Hydration of C₂S:** $$2C_2S + 4H \rightarrow C_3S_2H_3 + Ca(OH)_2$$
3. Hydration of C₃A
- **With excess H₂O:**
- C₃A + excess H₂O → (C₄AH₁₉ + C₄AH₈) *(metastable hydrates)*
- Over time → C₃AH₆ *(more stable, less soluble)*
- **With less H₂O (room temperature):**
- C₃A → C₃AH₆
4. Hydration of C₄AF
$$ C_{4}AF + CaSO_{4}\cdot2H_{2}O + Ca(OH)_{2} \rightarrow 3CaO(Al_{2}O_{3}\cdot Fe_{2}O_{3})\cdot3CaSO_{4}(aq)$$
**Role of Gypsum in Setting & Hardening**
- Added to cement to **delay setting**
**Calcination zone:**
$$\mathrm{CaCO_3 \rightarrow CaO + CO_2}$$
**Clinkering zone:**$$\begin{gather}2CaO + SiO_2 \rightarrow Ca_2SiO_4 \\
3CaO + SiO_2 \rightarrow Ca_3SiO_5\\3CaO + Al_2O_3 \rightarrow Ca_3Al_2O_6\\
4CaO + Al_2O_3 + Fe_2O_3 \rightarrow Ca_4Al_2Fe_2O_{10}\end{gather}$$***Grinding***
- Cooled **clinkers** are ground to fine powder in **ball mills**
- At final stage, **2–3% powdered gypsum** is added
- Prevents quick setting when cement contacts water
- **Gypsum acts as a retarding agent** for early setting
***Reaction (with gypsum)***
$$3CaO \cdot Al_2O_3 + xCaSO_4 \cdot 7H_2O \rightarrow 3CaO \cdot Al_2O_3 \cdot xCaSO_4 \cdot 7H_2O$$ (Tricalcium sulphoaluminate — insoluble)
***Packaging***
- Ground cement is stored in **silos**
- Automatically packed into bags (~**50 kg each**)
***Cement Hydration Timeline :***
- **Cement + Water → Paste**
- **1st day:**
- Hydration of **C₃A** and **C₄AF**
- **7th day:**
- Gelation of **C₃S**
- **28th day:**
- Gelation of **C₂S** and **C₃S**
***Setting and Hardening: Chemical Reactions***
- **Day 1**
- Hydration of **C₃A (tricalcium aluminate)** occurs within a day
- Paste becomes rigid → **Initial set / Flash set**
**Hydration Reactions**
(Calcium sulphoaluminate)
- **Day 2–7**
- After hydration of **C₃A**, **C₃S** begins to hydrate
- Forms **tobermorite gel (C-S-H)** and **crystalline Ca(OH)₂**
- Responsible for **initial strength** of cement
- Hydration of C₃S completes within ~7 days
- **Hydration Reactions**
$$
\mathrm{2(3CaO \cdot SiO_2) + 6H_2O \rightarrow 3CaO \cdot 2SiO_2 \cdot 3H_2O + 3Ca(OH)_2}
$$
Tobermorite gel + Crystalline calcium hydroxide
**OR**
$$
\mathrm{2C_3S + 6H_2O \rightarrow C_3S_2H_3 + 3Ca(OH)_2}
$$
C-S-H gel + Calcium hydroxide
- **After initial hydration (C₄AF & C₂S stage)**
- After hydration of **C₄AF (tetracalcium aluminoferrite)**, hardening occurs via **crystallization**
- Occurs along with hydration of **C₂S**
- Contributes to **later strength development** of cement
- **Hydration Reactions**$$\mathrm{4CaO \cdot Al_2O_3 \cdot Fe_2O_3 + 7H_2O \rightarrow 3CaO \cdot Al_2O_3 \cdot 6H_2O + CaO \cdot Fe_2O_3 \cdot H_2O}$$ Crystalline calcium aluminate hydrate + Ferrite gel
**OR**$$\mathrm{C_4AF + 7H_2O \rightarrow C_3A \cdot 6H_2O}$$ Hydrated calcium aluminate
- **Function of Gypsum (CaSO₄·2H₂O) in Cement**
- **C₃A (tricalcium aluminate)** reacts very rapidly with water → releases large amount of heat
- **Hydration Reaction**$$\mathrm{C_3A + 6H_2O \rightarrow C_3A \cdot 6H_2O + Heat}$$ Hydrated tricalcium aluminate
- After initial set, paste becomes **stiff**
- Adding **gypsum**:
- Retards dissolution of C₃A
- Forms **insoluble calcium sulphoaluminate**
- **Reaction with Gypsum** $$\mathrm{3CaO \cdot Al_2O_3 + xCaSO_4 \cdot 7H_2O \rightarrow 3CaO \cdot Al_2O_3 \cdot xCaSO_4 \cdot 7H_2O}$$ Insoluble calcium sulphoaluminate
- This reaction explains how gypsum **delays early setting** of cement
# glass
***Glass:***
- It is an amorphous, hard, brittle, transparent, or translucent, super cooled liquid of infinite viscosity, obtained by fusing a mixture of metallic silicates, most commonly of Na, K, Ca. and Pb
- It has no sharp melting point and definite structural formula
***Raw Materials for Glass Manufacturing:***
- **Silica (Quartz Sand)**
- Main raw material in commercial glass production
- Obtained from fine sand beds or pulverized sandstone
- **Soda Ash (Na₂CO₃)**
- Another main ingredient
- Lowers the **glass transition / melting temperature**
- **Lime (CaO)**
- Obtained from limestone
- Improves **chemical durability** of glass
- **Cullet (Recycled Glass)**
- Comes from waste glass
- Saves **raw materials and energy**
***Natural Resources:***
- Silica sand 72%
- Soda Ash 17%
- Lime 5%
- Other 6%
***Additional Substances:***
- **Lead** → increases brilliance and weight
- **Boron** → improves thermal and electrical resistance
- **Barium** → increases refractive index
- **Lanthanum oxide** → used for optical glasses
- **Iron & Cerium** → absorb infrared and UV wavelengths
- **Metallic oxides** → impart color
- **Manganese** → acts as decolorizing agent
- **Sodium sulfate & sodium chloride** → act as finishing agents
***Glass Manufacturing Process Flow***
- **Raw Materials** → **Melting**→ **Forming** → **Annealing** → **Inspection & Testing** → **Secondary Processing** → **Packing, Warehousing & Shipping**
***Silica Sand:***
- Three of most common rock forming minerals on earth are quartz, feldspar, and mica
- Chemical named: quartz sand / rock crystal
- Properties:
- Extremely heat durable
- Chemical stack resistance
- **Quartz:**
- silicon dioxide(SiO~2~) mineral, making it one of the most abundant minerals in the Earth's crust.
- Forms in various rock types, including granite, quartzite, and sandstone
- **Feldspar:**
- A large group of rock-forming silicate minerals that make up over 50% of Earth's crust.
- Found in igneous, metamorphic, and sedimentary rocks
- **Mica:**
- A group of minerals known for their excellent cleavage and platy appearance.
- Includes minerals like muscovite and biotite
- Common in various rock, including igneous, metamorphic, and sedimentary formations
- **Formation of Silica Sand:**
- **Naturally**: Mechanical & Chemical weathering of quartz-bearing igneous & metamorphic rocks
- **Chemical weathering**:
- Less stable minerals due to it breaking down to become silica sand
- More stable minerals:
- release to environment
- Carried by wind/ wave
- Sort by wave & stream action to form pure silica sand
- **Location & Integration of Silica Sand:**
- It is found below thin layers of overburden & soil as unconsolidated deposits
- It is abundant resource on earth crusts (44%) and occur throughout the world
- In India, Shankargarh block in Allahabad district of Uttar Pradesh is know for its high quality silica sand
- In U.S., Hudson Bay along the Red Deer River
- **World resources of Silica Sand:**
- Silica sand is abundant.
- Its extraction is limited by:
- geographic distribution
- quality requirements for some uses
- environmental restrictions
- Extraction of these resources is dependent on whether it is economic and are controlled by the location of population centers
- Purposes for Utilization of Silica Sand:
- History:
- Glass making & metallurgical activities few thousands of years ago
- Key raw material in ceramics, foundry & glass industrial revolution
- Today:
- Glass making, foundry casting, ceramics, filtration, specialist building applications, filters in numerous products, plastics, the manufacture of chemicals, metal & simulating oil production
- Important for today's information technology:
- raw material for silicon chips
- Plastics of computer mouses
- **Extraction of Silicon(Si):**
- Stripping of overburden (top soil & vegetation) by bulldozers & scraper
- Wet separation by washing the sand, passing through screens to remove roots & other organic matter
- gravity separation to separate silica sand from regular sand
- Finished silica sand is transported by trucks to plants for processing
- Oversized materials & residual clay are returned to mined pits
***Soda Ash:***
- Anhydrous sodium carbonate (Na~2~CO~3~)
- Texture: soft
- Color: grayish and white
- Appearance: lump / powder in nature
- **Formation:**
- Naturally:
- Erosion of igneous rock in the form of sodium deposits
- Transport by waters as runoffs & collect in basins
- When sodium comes in contact with CO~2~, it precipitates out as sodium carbonate
- **Location & Integration of Soda Ash:**
- Integrated as sodium-rich waters (brines) / extensive beds of trona interbedded with sodium minerals
- Trona is a hydrated sodium carbonate and bicarbonate
- Large soda ash deposits:
- U.S, Mexico, Canada, Kenya, Botswana, Uganda, Peru, Germany, India, Egypt, South Africa & Turkey
- World's largest trona deposit:
- Green River Basin of Wyoming, estimated to have 47 billion tons of soda ash
- **Purposes and Utilization of Soda Ash:**
- History:
- Early Egypt: make glass & soap
- Early Roman: make glass, bread & pharmaceutical(medicine) purpose to cure chronic & skin rashes
- Important Uses:
- - **Glass manufacture** (49%)
- **Chemical production** (27%)
- **Soap & detergents** (11%)
- **Water treatment** (2%)
- Industrial Applications:
- Glass fiber manufacture
- Cleaning preparations
- Petroleum refining
- Metallurgical refining / metal refining
- Removal of sulfur from smokestack emissions (3%)
- Mineral processing (mining)
- Pulp & paper manufacturing
- Sodium compounds manufacturing
- Textile processing
- Extraction of Soda Ash:
- Quarrying of trona bed that contains sodium
- Could be manufactured synthetically through Solvay process by using salt, ammonia & limestone
***Lime:***
- Include hydrated lime & quicklime (CaO)
- Only quicklime can use to make glass
- **Location & Integration of Lime**:
- Underneath the topsoil and siltstone (composed mostly of broken grain of quartz):
- Associated in:
- Limestone
- Marine organisms on seabed, e.g. seashells
- **Formation of Lime:**
- Marine organisms dissolve CO~2~ & extract Calcium from seawater to from calcium carbonate
- Buried under sediments of seabed after death
- Limestone under head & pressure on the remains of marine organisms
- Purposes and Utilization of Lime
- Historical Uses:
- Ancient Egyptian civilization used lime for **plaster and mortar**
- Modern Uses:
- Extensively used in:
- **Glass manufacturing**
- **Pulp & paper industry**
- **Steel mills**
- Other applications:
- **Municipal & industrial water/wastewater treatment**
- Additive for **road stabilization** and **construction projects**
- In the U.S., **>90% of lime production** is used for **chemical and industrial purposes**
- ***Extraction of Lime:***
- **Quarrying**
- Limestone obtained from **quarries (trona bed)**
- **Transportation**
- Transported to crushing plants via **trucks or rail**
- **Calcination Process**
- Limestone/chalk (**CaCO₃**) heated in kiln to ~**900°C**
- **CO₂ is released** and **CaO (lime)** is produced
- Reaction $$\mathrm{CaCO_3 \rightarrow CaO + CO_2 \uparrow}$$
- ***Effects pose by the Extraction of Minerals Sites for making glass:***
- Location of mineral sites: mostly located in developing/underdeveloped countries near poor communities, that results in social and environmental impacts
- Environmental Impacts:
- create large amount of rubbish on the extracted sites, causing serious environmental pollution and degradation
- Water contamination:
- Blasting & digging during extraction process produce wastes & easily get into the water as runoff
- In waste disposal activities, systems direct waste into rivers & tributaries
- Inadequate rehabilitation of disturbed areas remain wastes behind the sites
- Soil Disturbance:
- stripping of the overburden will loosen the soil cause soil erosion
- loss of water in soil through evaporation
- Loss of nutrient & mineral in soil:
- Wet separation process in the manufacturing process of silica sand will wash away minerals and nutrients in soil, that is important for vegetation growth, e.g. lack of magnesium
- Social Impacts:
- Contamination of ground water for nearby communities:
- Runoffs from extraction sites contaminate the water & may transport to nearby communities
- Drinking water & agricultural resources is polluted
- Disease:
- Communities may get diseases through consuming the contaminated water / seafood
- New diseases may be introduced to communities through mine workers from communities far away
- Fodder, fuel wood and glazing communities:
- Businesses being affected due to environmental pollution
- Agricultural communities:
- Water for irrigation is being contaminated, loss of water resources for drainage
- Plants & crops die and cattle may get disease
- Local communities and villages:
- Loss in food security for self-supply communities
- Disruption of local economics system:
- Communities nearby cannot depend on their land for production for export and economics benefits e.g. case of limestone mining in Uttaranchal
- Contamination sites requires large capital for rehabilitation
- May require communities living around the extraction sites to pay for rehabilitation
- Taxpayer may also need to pay for part of the rehabilitation program of disturbed sites
***Transportation of natural resources for glass manufacturing plant:***
- Development of **transport systems**, roads, and network expansion
- Enables transport of raw materials to plants **farther from sources**
- **Nearby transport:** trucks or railways
- **Long-distance transport:** ships
- Benefits
- Supports development of transportation infrastructure in regions
- No significant environmental or community side effects
***Automation in Glass Manufacturing:***
- First **automated bottle machine** developed in **1905**
- Nowadays:
- Most glass containers are produced using **advanced machines**
- Manufactured in **large automated factories**
- Controlled by **computers**
- Results: **cheaper production** and **better quality**