৪৯তম বিসিএস ⎯ ফলিত রসায়ন [৫৪১]

Precipitation of non-sugar impurities:
Lime reacts with organic acids, proteins, and other non-sugar compounds, forming insoluble calcium salts that can be removed by sedimentation or filtration.
This clarifies the juice and reduces impurities that could affect sugar crystallization.

Stabilizing pH:
Cane juice is naturally acidic. Liming raises the pH to around 7–8, which is favorable for subsequent sugar clarification and evaporation.
A stable pH also reduces the rate of sucrose inversion (breakdown into glucose and fructose).

Why not the other options?

ক) To reduce color of juice only: Liming indirectly helps in color reduction, but the main aim is impurity removal and pH stabilization.
গ) To neutralize sucrose and increase inversion: Liming actually prevents inversion, not increases it.
ঘ) To remove all soluble salts completely: Liming removes some impurities, not all soluble salts.

Cell structure of sugar beet:
Beet roots are made of parenchyma cells containing sucrose in the vacuoles.
Sucrose is water-soluble, and hot water efficiently leaches it out without crushing the fibers.

Efficiency:
Diffusion allows high extraction efficiency (~95–98%) without breaking down the beet’s fibrous structure.
Milling (like in sugarcane) would require heavy mechanical crushing and can cause higher sugar losses.

ক) Sugar beet has higher fiber content than sugarcane: Actually, sugar beet has lower fiber content than cane, so milling is less necessary.

খ) Sugar beet juice is highly viscous: Beet juice is less viscous than cane juice; diffusion is not for viscosity.

ঘ) Milling causes high sucrose loss in beet compared to cane: Milling is not typically used; the main reason is the water-soluble nature of sucrose, not direct sugar loss.

Liming (Addition of lime, Ca(OH)₂):
Raises pH of juice and precipitates many non-sugar impurities (proteins, organic acids).

​Carbonation (or sometimes Sulphitation in sugarcane factories):
1.  In carbonation, carbon dioxide (CO₂) is bubbled through limed juice.
2. Forms calcium carbonate (CaCO₃) precipitate which traps remaining impurities.

Filtration/Settling:
The precipitate is removed by clarification tanks or filters, leaving a clear juice.
​
​খ) Sulphitation only: Sulphitation is an alternative clarification method (mainly in beet sugar), but clarification usually involves multiple steps.
গ) Vacuum evaporation only: Evaporation concentrates sugar, it does not remove impurities.
ঘ) Centrifugation and crystallization: These are later steps in sugar production, after clarification and evaporation.

In sugar manufacturing, after juice clarification, the next step is evaporation to concentrate the juice. A multiple-effect evaporator is widely used because it improves energy efficiency. Here’s why:

How it works:
The evaporator has multiple chambers (effects).
Steam heats the juice in the first effect, generating vapor.
The vapor from the first effect is used as the heating medium for the second effect, and so on.

Main advantage:
This arrangement maximizes steam utilization and reduces overall energy consumption.
For example, in a 4-effect evaporator, the steam used in the first effect indirectly heats the next three, saving up to 70–80% of energy compared to a single-effect evaporator.

ক) Reduction of sucrose inversion: While controlled heating reduces inversion, this is not the main advantage.
খ) Increased number of crystals formed: Crystallization happens after evaporation, not during.
ঘ) Elimination of lime requirement: Liming is part of clarification; evaporation doesn’t remove the need for lime.

he major difference between sugarcane and sugar beet processing lies in the clarification method:

Sugarcane processing:
Common method → Sulphitation (SO₂ gas passed through limed juice).
Purpose: Bleaching the juice, controlling pH, and removing impurities.

Sugar beet processing:
Common method → Carbonation (CO₂ bubbled through limed juice).
Purpose: Precipitation of impurities as calcium carbonate (CaCO₃).

In sugar manufacturing, crystallization happens in vacuum pans because boiling under vacuum reduces the boiling point, minimizing sucrose inversion.
The concentrated syrup from evaporators enters the vacuum pan.

Steps leading to a strike:
1. Seeding: A small amount of fine sugar crystals (seed crystals) is added to initiate crystallization.
2. Crystal Growth: More syrup is added gradually while boiling continues, causing the crystals to grow to the desired size.
3. Formation of Massecuite: A thick mixture of sugar crystals and mother liquor (molasses) forms.
When the crystals reach the required size, the entire batch of massecuite is discharged from the pan into crystallizers.

This discharged batch is called a strike.

In sugar crystallization, clarification aims to remove impurities like proteins, gums, colloids, and suspended solids. Among these, starch is the most critical because:
Why starch is problematic:
Starch forms viscous colloidal suspensions that do not settle easily.
It creates a gel-like film on the surface of growing sugar crystals, which:
Slows down crystal growth
Leads to formation of false grain (unwanted fine crystals)
Reduces crystallization efficiency

Impact on sugar quality:
Starch makes the massecuite thick and difficult to handle in crystallizers and centrifugals.
Final sugar may have dull color and poor purity.

Lower Boiling Point Under Vacuum:
At atmospheric pressure, syrup boils at around 100 °C or higher.
Under vacuum, the boiling point drops to 60–70 °C (depending on pressure).

Prevents Caramelization and Inversion:
At high temperatures, sucrose undergoes:
     Caramelization → sugar decomposition into brown compounds.
     Inversion → conversion of sucrose into glucose and fructose.

Both reduce sugar yield and affect quality.
Vacuum boiling keeps temperature low, minimizing these losses.

Additional Benefits:
Produces better color and purity indirectly (by avoiding overheating).
Allows controlled crystal growth, preventing false grain formation.

Molasses is the mother liquor left after sugar crystals have been removed by centrifugation. It still contains:
     30–35% sucrose and reducing sugars
    Organic compounds and minerals
 
​Since it is rich in fermentable sugars, its primary industrial use is:
1. Alcohol and ethanol production through fermentation (using yeast).
2, Products include:
Ethanol (industrial and fuel alcohol)
Portable spirits (like rum)
Acetone, butanol (via fermentation processes).

Bagasse is the fibrous residue left after extracting juice from sugarcane during milling. It typically contains:
~45–50% moisture
~45% fiber (cellulose, hemicellulose, lignin)
Small amount of sugar and ash

Main Uses of Bagasse:

1. Boiler Fuel:
Bagasse is burned in sugar factory boilers to produce steam for:
Running turbines (electricity)
Evaporation and crystallization processes
This makes sugar factories energy self-sufficient.

2. Paper and Pulp Manufacturing:
Due to its high cellulose content, bagasse is an excellent raw material for making:
Writing and printing paper
Packaging materials
Cardboard

In sugarcane juice clarification, lime (Ca(OH)₂) is added to:
       Neutralize organic acids
       Raise pH to about 7.0–7.2
       Facilitate precipitation of impurities (phosphates, proteins, gums)
However, excess lime beyond the optimum causes the following issues:

1. Excess Ca²⁺ ions remain in solution:
When CO₂ is later introduced (carbonation) or natural CO₂ in juice reacts, excess Ca²⁺ + CO₂ → CaCO₃.
This leads to excessive CaCO₃ precipitation, which causes:
Scaling in heaters, evaporators, and pipelines.
Entrainment of sugar in precipitates → high sugar loss.

2. Alkaline degradation of sucrose:
Too high pH (>8.5) can cause alkaline degradation of sucrose into color-forming compounds (alkali color).

Given:
Water to evaporate = 11,000 kg
Steam economy = 2.5 kg vapor per kg steam → 1 kg steam evaporates 2.5 kg water

Steam required:

Steam required=Water to evaporate/Steam economy=11,000/2.5=4,400 kg steam
Steam required= Steam economy/Water to evaporate =2.5/11,000=4,400 kg steam

Bagasse needed:
1 kg bagasse → 2.2 kg steam

So,
   Bagasse required=4,400/2.2=2,000 kg

The sugar industry in Bangladesh faces several challenges, and one of the major technical problems is the low recovery of sugar from sugarcane. This is due to:

1. Poor quality of sugarcane:
       Low sucrose content, high fiber, and delayed harvesting reduce juice quality.
2. Inefficient processing;
  ​     Outdated mills, improper clarification, and inefficient crystallization lead to higher sugar loss.
3. Climatic and agronomic factors:
        Short harvesting season and unpredictable rainfall affect cane yield and sucrose content.

Bangladesh has several sugar mills, but they cannot meet the country’s total sugar demand.

Reasons for low domestic production:

      1.Low sugarcane yield and quality: Poor sucrose content and short harvesting seasons.
      2.Inefficient processing: Old and outdated mills reduce sugar recovery.
      3.Limited cultivated area: Sugarcane cultivation is constrained by land use and water availability.

As a result, Bangladesh imports a significant portion of sugar to meet the consumption demand of households and the food industry.

The high production cost of sugar in Bangladesh is primarily due to the low quality of locally grown sugarcane, which has:

1.Low sucrose content:
     Less sugar is extracted per ton of cane, reducing efficiency.

2.High fiber and impurities:
     More energy and chemicals are required for extraction and clarification.

3.Short harvesting season and losses during transport:
     Cane deteriorates quickly after harvest, further reducing sugar recovery.

Bangladesh has several discovered coalfields, but they differ in calorific value and usability:

1.Barapukuria Coalfield (Dinajpur District):
 The only actively mined coalfield in Bangladesh.
 Calorific value: ~5,200–5,500 kcal/kg (higher than other deposits).
 Mostly sub-bituminous type, suitable for power generation.

2.Other coalfields:
 Jamalganj, Phulbari, Dighipara: Lower calorific value (~3,500–4,500 kcal/kg), more lignitic in nature.

Phulbari Coalfield (Dinajpur District) is estimated to have the largest coal reserve in Bangladesh, with reserves of approximately 500–600 million tons.
It is considered anthracite to bituminous coal, suitable for power generation, though mining has not yet begun due to environmental and social concerns.
Other coalfields for comparison:

1. Barapukuria: ~390 million tons (currently mined).
2. Jamalganj: ~200 million tons.
3. Khalashpir: ~60–100 million tons.

Most of the coal deposits in Bangladesh are found in the Gondwana and Tertiary basins, but the majority belong to the Tertiary (Miocene) age.

Characteristics of Tertiary (Miocene) coal in Bangladesh:
  Found in northwestern districts (Dinajpur, Rangpur).
  Sub-bituminous to bituminous type, suitable for power generation.
  Formed from plant materials buried in deltaic and swampy environments during the Miocene epoch (~23–5 million years ago).

Other ages:
    Permian (Gondwana): Older coals, not significant in Bangladesh.
    Jurassic and Quaternary: No major coal deposits in Bangladesh from these periods.

Phulbari Coalfield is known for having shallow coal seams, typically less than 100 meters deep in many areas.

This makes it suitable for open-pit (surface) mining, unlike deeper coalfields which require underground mining.

Other coalfields:
     Barapukuria: Deeper seams (~120–180 m), mined by underground methods.
​      Khalashpir: Also deeper, underground mining required.
​      Dighipara: Moderate depth, but still more suited to underground mining.

Bangladesh has several discovered coalfields, mainly in the northwestern region: Phulbari, Barapukuria, Jamalganj, Khalashpir, and Dighipara.

Estimated reserves by field:
​​ Coalfield ⇒ Estimated Reserve (million tons​)                                                
​  Phulbari ⇒ 500–600                                             
​  Barapukuria ⇒ ~ 390                                              ​                                                 
 ​ Jamalganj ⇒ ~ 200                                                   
​  Khalashpir ⇒ ~ 60–100                                                 
​  Dighipara ⇒ ~ 60–100.

Jamalganj Coalfield is located in the northern part of Bangladesh and is known for having coal seams at very large depths, typically over 300 meters.

Challenges due to extreme depth:

Underground mining required: Open-pit mining is not feasible.
High cost and technical difficulty: Deep shafts, ventilation, and safety measures increase production costs.
Limited accessibility: Makes extraction slower and more expensive compared to shallower fields like Phulbari.

Other factors:
Low calorific value: Not as severe as depth; coal is still usable for power.
High sulfur content: Relatively low in Jamalganj coal.
Water table fluctuation: Present but manageable with proper mining techniques

Coal rank indicates the degree of coalification, i.e., how much plant material has transformed into carbon-rich coal under heat and pressure over geological time.

Critical property:
Fixed carbon content increases as coal rank rises:
  Lignite: Low fixed carbon (~25–35%) → high moisture
  Sub-bituminous: Moderate fixed carbon (~35–45%)
  Bituminous: Higher fixed carbon (~45–85%)
  Anthracite: Very high fixed carbon (~85–95%) → hardest, cleanest burning

Other properties:
Volatile matter: Decreases with rank but is secondary to fixed carbon.
Sulfur content: Impacts environmental emissions, not rank.
Ash fusion temperature: Important for combustion behavior, not rank.

The reaction  is called the Boudouard reaction.

Details:
Type: Endothermic reaction (absorbs heat)
Purpose in coal gasification:
   Converts solid carbon (coal/coke) and carbon dioxide into carbon monoxide (CO), which is a useful syngas component.
    Helps in gasification efficiency at high temperatures (~800–1000°C).

ক) Water-gas shift reaction:
Reaction: CO + H₂O → CO₂ + H₂
Purpose: Adjust H₂/CO ratio, produces hydrogen.

গ) Methanation reaction:
Reaction: CO + 3H₂ → CH₄ + H₂O
Purpose: Produces methane, not CO.

ঘ) Partial oxidation reaction:
Reaction: C + ½ O₂ → CO
Involves oxygen, not CO₂.

The ASTM (American Society for Testing and Materials) coal classification system primarily classifies coal based on energy content, i.e., its calorific value.

Dry Ash-Free (DAF) basis:
   Removes the effect of moisture and ash, giving a clearer measure of the coal’s true energy content.

​ASTM classification typically categorizes coal as:
     Anthracite → highest calorific value, low volatile matter
     Bituminous → high calorific value, varying volatiles
    Sub-bituminous → moderate calorific value
    Lignite → low calorific value

Coal carbonization in coke ovens involves heating coal in the absence of air to produce coke, a solid carbon material used in steelmaking.

During this process, several volatile organic compounds are released. Among them, PAHs (polycyclic aromatic hydrocarbons) are of major environmental concern because:

1. They are toxic, mutagenic, and carcinogenic.
2. They can pollute air, soil, and water if released untreated.
3. They persist in the environment and bioaccumulate.

Underground Coal Gasification (UCG):
A method to convert in-situ coal into syngas (CO + H₂ + small amounts of CO₂, CH₄) without mining.

​Role of oxygen and steam injection:

1. Partial Oxidation with Oxygen:
Reaction: C + ½ O₂ → CO (exothermic)
Provides heat to sustain endothermic reactions in the coal seam.

2. Steam Injection:
Reaction: C + H₂O → CO + H₂ (endothermic)
Converts solid carbon into syngas components (CO + H₂).

Coal carbonization processes:

1. Low-Temperature Carbonization (LTC):
Operates at 400–700°C in absence of air.
Produces coke, coal tar, oils, and gases.
Tar and aromatic hydrocarbons yield is highest because:
       Moderate heat favors decomposition of complex organics into condensable hydrocarbons.

​2. High-Temperature Carbonization (HTC):
Operates at >1000°C.
Produces hard coke and gases.
Tar yield is lower; most organics are cracked into permanent gases (CO, H₂, CH₄).

3. Direct Combustion in Boiler:
Complete oxidation → CO₂ and H₂O
Very little tar or aromatics produced.

4. Gasification in Fluidized Bed:
Partial oxidation or reaction with steam/air
Produces syngas (CO + H₂), minimal tar and aromatics.

Coal Combustion:
Reaction: 
​ C + O₂ → CO₂ (complete oxidation)
Produces heat and mainly carbon dioxide and water vapor.
Purpose: energy generation.

Coal Gasification:
Reaction: Partial oxidation with limited oxygen, air, or steam:
C + ½ O₂ → CO
C + H₂O → CO + H₂
Produces syngas (CO + H₂) rather than complete combustion products.
Purpose: chemical feedstock or fuel gas, not just heat.

Acid rain is formed when sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) react with water in the atmosphere to form sulfuric acid (H₂SO₄) and nitric acid (HNO₃).

Reaction example:
 SO₂+H₂O→H₂SO₃(sulfurous acid)
 2SO₂+O₂+2H₂O→2H₂SO₄(sulfuric acid)

In coal utilization, sulfur in coal is oxidized to SO₂, which is the primary contributor to acid rain.

1. Coal Gasification:
Converts coal into syngas (CO + H₂) in a controlled environment with limited oxygen and/or steam.
Before burning the syngas, pollutants like:
Sulfur compounds (H₂S)
Particulates

can be removed efficiently.
Results in cleaner gas for power generation or chemical synthesis.

2. Direct Combustion:
Coal is burned directly → CO₂, SO₂, NOₓ, particulates are emitted into flue gas.
Pollution control is more difficult and less efficient.

Step location: After liming but before evaporation.
What happens:
Raw cane juice is first treated with milk of lime (Ca(OH)₂) to neutralize acids and precipitate impurities.
Then SO₂ gas is bubbled through the juice. SO₂ dissolves in water forming H₂SO₃ (sulfurous acid):
SO₂ + H₂O ⇌ H₂SO₃

This slightly acidifies the juice (pH ~ 7 to 7.2), which helps control alkalinity left from liming.
SO₂ is a reducing agent, so it bleaches colored compounds, improving the final sugar color.

1.In the carbonation process (used in beet sugar manufacturing), the raw juice is first treated with milk of lime (Ca(OH)₂) to neutralize acids and precipitate some impurities.
2.Then CO₂ gas is bubbled through the juice:
  Ca(OH)₂+CO₂→CaCO₃↓+H₂O
3.Calcium carbonate (CaCO₃) precipitates and acts as a filter aid, trapping non-sugars (proteins, organic acids, colloids) and removing them from the juice.
4.This clarification step improves purity before evaporation and crystallization.

Other options :
ক) To remove sucrose crystals from solution → Crystallization happens much later, not during carbonation.
খ) To reduce lime requirement → CO₂ does not reduce lime demand; it reacts with lime to form CaCO₃.
ঘ) To decolorize juice directly → Color removal is minor; main purpose is impurity precipitation, not bleaching.

1. Clarification is the step where impurities (like proteins, colloids, and calcium salts) are removed from raw juice using lime + CO₂ (carbonation) or SO₂ (sulphitation).
2. After clarification, the juice is clear but still mostly water (~85–90%).
3. The next step is evaporation in multiple-effect evaporators:
    Concentrates the juice to a thick syrup (~65–70% solids).
    Prepares the juice for crystallization in the subsequent stage.

Other options:
ক) Sulphitation → Done before clarification in cane sugar processing.
খ) Liming → Also done before clarification to adjust pH and precipitate some impurities.
গ) Carbonation → A clarification method, occurs before evaporation.

1.Thin juice from beet sugar extraction contains mostly water (~85–90% water).
2.Before crystallization, it is concentrated into thick juice (~65–70% solids) using multiple-effect evaporators.
3.Purpose:
    Increase sucrose concentration → makes crystallization feasible.
    Reduce energy consumption → less water needs to be evaporated during crystallization.
     Prepares the syrup for efficient sugar crystal formation.

Other options:
ক) To remove molasses early → Molasses separation happens after crystallization, not before.
গ) To improve bleaching efficiency → Bleaching is done earlier (clarification or sulphitation).
ঘ) To neutralize residual alkali → Neutralization occurs during liming or carbonation, not during concentration.

In vacuum pan boiling, sugar crystallization occurs from a supersaturated syrup.
Crystal size is mainly controlled by:
1.Rate of supersaturation: Slow, controlled supersaturation favors larger crystals; rapid supersaturation produces smaller crystals.
2.Seeding (strike): Introduction of seed crystals provides nucleation sites and affects final crystal size.

Other options:
ক) Purity of molasses → Affects yield and color, but not directly crystal size.
গ) Color of the juice → Only relates to product quality.
ঘ) Bagasse moisture content → Relevant for energy efficiency, not crystal formation.

1.Press mud (also called filter cake) is the solid residue obtained from sugar juice clarification after filtration.
2.It is rich in organic matter, calcium, and some residual sugars.
3.Uses:
       Soil conditioner – Improves soil structure and fertility.
       Fertilizer – Provides nutrients like calcium and some micronutrients.

Other options:
ক) Glass manufacturing → Not relevant; silica and sand are used instead.
খ) Boiler fuel → Bagasse is used as fuel, not press mud.
ঘ) Alcohol production → Molasses is used, not press mud.

1.Molasses, a by-product of sugar manufacturing, is rich in sugars and can be used as a fermentation substrate.
2.Certain microorganisms (e.g., Clostridium acetobutylicum) ferment molasses to produce:
      Acetone
      Butanol
      Sometimes small amounts of ethanol (ABE fermentation).

Other options:
ক) Polyethylene → Derived from petroleum/ethylene, not fermentation.
গ) Caustic soda → Produced by electrolytic processes, not fermentation.
ঘ) Cement clinker → Produced by heating limestone and clay, unrelated to molasses.

1.Bagasse, the fibrous residue left after juice extraction from sugarcane, is used as a fuel in boilers.
2.Cogeneration plants in sugar mills:
       Burn bagasse to produce steam for the mill.
        Generate electricity for internal use and sometimes for export to the grid.
3.This reduces reliance on external electricity, making the mill more energy self-sufficient.

Other options:
খ) Increasing sucrose recovery → Depends on extraction efficiency, not energy generation.
গ) Improving crystallization → Related to juice concentration and purity, not cogeneration.
ঘ) Lowering lime consumption → Depends on juice treatment methods, not bagasse use.

Bagasse ash is the residue left after burning bagasse in boilers.
It contains a high percentage of silica (SiO₂), often 50–60% or more, depending on combustion conditions.

Applications:
1. Cement additive – Acts as a pozzolanic material, improving strength and durability.
2. Brick manufacturing – Provides silica, which helps in forming strong ceramic-like structure.

Other options:
ক) CaCO₃ → Found in limestone, not significant in bagasse ash.
গ) MgCO₃ → Not a major component.
ঘ) Na₂O → Minor component, not responsible for cement/brick utility.

Furfural is an industrial chemical used in resins, solvents, and plastics.
It is primarily produced from pentose-rich residues.
Bagasse, the fibrous residue from sugarcane after juice extraction, contains hemicellulose, which is rich in pentoses (like xylose).
Acid hydrolysis of bagasse pentoses produces furfural.

Other options:
ক) Molasses → Rich in sucrose (hexose), used for ethanol, acetone-butanol fermentation, not furfural.
গ) Press mud → Mainly organic matter and minerals, not high in pentoses.
ঘ) Filter cake → Similar to press mud, used as soil conditioner, not for furfural production.

Sugar Recovery in Bangladesh Sugar Mills
The average sugar recovery rate in Bangladesh has been approximately 6.85% in recent years, with a decline from 7.68% in 1992 to 6.85% in 2015.
​
​Factors Influencing Sugar Recovery
Several factors contribute to the relatively low sugar recovery rate in Bangladesh:
   1. Inefficient Extraction Methods: Outdated equipment and processing techniques lead to suboptimal extraction of sugar from sugarcane.
   2. Limited Crushing Duration: Mills often operate for only two to two and a half months annually due to insufficient raw material supply, limiting the total sugar production.
   3. Sugarcane Quality and Yield: Lower yields per hectare and the diversion of sugarcane for jaggery production instead of sugar manufacturing affect the overall recovery rate.
​
​While the current average sugar recovery rate in Bangladesh is around 6.85%, historical data indicates that the average has been in the 12–14% range. This highlights the need for modernization and efficiency improvements in the sugar industry to enhance sugar recovery rates

Most sugar mills in Bangladesh are government-owned and outdated, using obsolete equipment and inefficient processes.
Adopting modern sugar refining technologies (like improved juice extraction, continuous crystallization, and advanced evaporation systems) requires significant capital investment.
High upgrade costs are the primary barrier to modernization.

Other options:
ক) Excessive mechanization of harvesting → Harvesting is mostly manual in Bangladesh, so mechanization is not an issue.
খ) Unavailability of sulfur dioxide → SO₂ is available and used in sulphitation; not a major limitation.
ঘ) Lack of sufficient bagasse for fuel → Bagasse is abundant as a by-product, often underutilized, so this is not a limitation.

Bangladesh Sugar Mills Corporation and Bangladesh Food and Allied Industries Corporation formed by Presidential Order No. 27 (Order No. 27 of 1972) after the independence of Bangladesh merged the two corporations by President's Order No. 25 from July 1, 1976 (revised) Bangladesh Sugar and Food Industries Corporation (BSFIC) was formed. At present, BSFIC is being managed by a board consisting of 1 chairman and 5 directors appointed by the government as per the Nationalization of Bangladesh Industries Act 2018. In the financial year 2023-2024, the activities of the corporation are continuing with 15 sugar mills, 1 engineering factory and 2 commercial establishments. It also has a distillery plant and a bio-fertilizer plant with Keru & Company (Bangladesh) Limited.
​
​Aims & Objectives of the Corporation:
1. Increase in sugar production volume and extraction rate;
2. Supplying high yielding sugarcane and sugar mills using advanced technology;
3. Institutional capacity building and factory modernization;
4. Consolidation of the organization's financial position through product marketing, market expansion and cost reduction;
​
​Source: বাংলাদেশ চিনি ও খাদ্য শিল্প করপোরেশন​

The quality of sugarcane is primarily measured by its sucrose content, which directly affects sugar recovery in mills.

High-sucrose hybrid varieties:
    Produce more sugar per ton of cane.
    Reduce losses during processing.
    Are disease- and drought-resistant, improving overall yield and consistency.

Sugar beet requires temperate climates with cool winters and well-drained loamy soil.

Bangladesh has a tropical climate with high temperatures and humidity, which is unsuitable for sugar beet cultivation.

As a result, cane sugar is preferred, which grows well under Bangladesh’s soil and climate conditions.

Other options:
খ) Lack of CO₂ for carbonation → CO₂ supply is not a cultivation issue; it’s part of sugar processing.
গ) Low demand for beet sugar → Demand exists, but cultivation is limited by climate.
ঘ) Excessive mechanization requirement → Mechanization is helpful but not the primary limiting factor.

Barapukuria Coal Mine: Bangladesh’s Sole Active Underground Mine.

Location: Chowhati, Parbatipur, Dinajpur District, Bangladesh.

Operator: Barapukuria Coal Mining Company Limited (BCMCL), a subsidiary of Petrobangla.

Mining Method: Underground mining utilizing longwall mining techniques.

Production: Approximately 1,750 to 2,356 tons of coal per day.

Total Reserves: Estimated at 390 million tons, with about 64 million tons considered extractable.

Operational Start: Commercial production commenced in early 2005.

Power Plant: The mined coal primarily fuels the Barapukuria 525 MW coal-fired power plant.

Bangladesh coal (mainly from Barapukuria, Jamalganj, Khalashpir, Dighipara) is:

​Non-coking → Cannot form strong coke required for steel-making in blast furnaces.
High ash content → Reduces its suitability for metallurgical applications but is tolerable for thermal power generation.

​Therefore, it is mainly used as fuel in coal-fired power plants rather than for coke production.

Other options:

ক) High sulfur and phosphorus content → These affect steel quality but Bangladesh coal generally has low sulfur, so this is not the main limitation.
গ) Very low moisture content → Low moisture is advantageous for both power and coke, not a limitation.
ঘ) High calorific value with low volatile matter → High calorific value favors combustion; it doesn’t make coke production difficult.

Coal rank increases from lignite → sub-bituminous → bituminous → anthracite.

Lignite (brown coal):
Highest moisture content: 30–60%
Lowest calorific value: ~10–20 MJ/kg

Soft, crumbly, mainly used for nearby power generation.

Higher-rank coals (bituminous, anthracite):
Lower moisture
Higher carbon content
Higher calorific value

Anthracite has the highest carbon content and calorific value.

Coal carbonization (coking process) involves heating coal in the absence of air.

During this thermal decomposition, the volatile matter is driven off.

The volatiles primarily consist of:
Hydrocarbons (methane, ethylene, benzene, etc.)
Ammonia (NH₃)
Tar vapors (condensable organics)

The remaining solid is coke, mainly carbon with low volatiles, used in metallurgy.

Open-pit coal mining exposes large amounts of sulfide-containing rocks (like pyrite, FeS₂) to air and water.

This leads to acid mine drainage (AMD):
 2FeS₂ + 7O₂ + 2H₂O → 2Fe²⁺ + 4SO₄²⁻ + 4H⁺

Acidic water can contaminate rivers and groundwater.

Large-scale excavation causes land subsidence, soil erosion, and habitat destruction.