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Calcium carbide is manufactured in four grades according to the amount of acetylene generated when reacting with water.
Industrial grade
The most commonly produced and calcium carbide price industrial-grade is typically 80% or purer. This grade is designed for large scale acetylene production.
Acetylene production grade
It contains about 70-80% calcium carbide. This is used in production where acetylene is the main product.
Chemical grade
Often also called laboratory grade. Usually contains at least 99% calcium and carbon elements. It is used in scientific research or high value acetylene production.
Reagent grade
Also known as analytical grade. This grade is typically 99.9% pure. It is used in pharmaceuticals, pesticides, and other chemical products.
Agriculture
Calcium carbide is used in calcium carbide and water reaction to produce acetylene. The acetylene gas is then used to ripen fruits like bananas, mangoes, and tomatoes during shipping and storage. The acetylene acts as an alternative to ethylene.
Manufacturing
It is used in calcium carbide gas welding and cutting metals. Its high temperature flame makes it ideal for cutting and fusing metals like steel, aluminum, and copper. Carbide also produces phosphorous which is used to manufacture phosphate fertilizers.
Chemical industry
When combined with nitrogen, calcium carbide produces cyanamide which is ideal for fertilizer production. Cyanamide is used to manufacture thiophosphate, a fertilizer rich in nitrogen. Phosphate fertilizers improve soil quality and boost crop production.
Mining operations
Used in producing acetylene which is utilized in the mineral excavation, hence improving productivity in mining zones. Calcium carbide is also used in underground fire prevention. Acetylene is applied to produce flame safety lamps to minimize fire risk in underground mines.
Steel industry
When added to molten iron, calcium carbide helps remove impurities hence improving the iron’s quality and make it stronger. Calcium carbide is also a source of carbon used in phosphorous removal.Purified iron can be transformed to high-quality steel suitable for manufacturing car parts, construction beams, tools, and appliances.
Emergency lighting
Calcium carbide is used to manufacture acetylene lamps for mining and underground works. The lamp is the safest option for lighting areas prone to fire, hence widely used.This is after the calcium carbide and water reaction that emits acetylene gas used in the lamps. Acetylene lamps are ideal for fire prevention in tunnels and mines.
Chemical formula
Calcium carbide is represented as CaC₂ in chemical formula. It consists of two carbon atoms and one calcium atom.
Appearance
Looks like grayish black or white crystalline solid. Depends on the purity and source. High purity is usually grey while lower purity looks like black granules.
Solubility
Insoluble in water and most organic solvents. Reacts violently with water to produce acetylene gas and calcium hydroxide a danger solvent who’s reaction with water produces acetylene gas.
Molar mass
Weighs approximately 64.10 grams per mole for the carbon and calcium components.
Acetylene generation
Generates 294 kilojoules per mole when reacting with water. This makes it an ideal source of acetylene in remote areas.
Reactivity
Highly reactive with water, oxygen, sulfur, phosphorus, nitrogen, nonmetals, and metals like copper to form acetylene and other compounds. Must be stored airtight in a closed container away from moisture to prevent explosive gas formation.
Calcium carbide exists mainly in two structures
Pyramidal structure, one of the two carbon atoms is bonded to the calcium atom with a single covalent bond forming a stable structure. This form is more stable and common in high purity samples. Tetragonal structure, this structure is less common and unstable due to steric hindrance between the carbon atoms. Typically found in lower purity calcium carbide samples.
Acetylene generation
Usually used for acetylene production when combined with water. Calcium carbide usually reacts with water to generate acetylene gas and calcium hydroxide solution used in welding.
Acetylene torch
When the acetylene gas and oxygen are mixed in the torch, the mixture is then emitted through the welding tip. The mixing of the two gases produces a highly flammable mixture used in cutting and welding. Proper safety precautions are needed when handling torches and storing gas cylinders, including wearing personal protective equipment like gloves, goggles, and a face shield.
Acetylene lamps
Acetylene gas is used in lamps for underground mining to provide safety. It was used by miners in areas exposed to fire. The flame safety lamp has a flame that indicates if methane or other explosive gases are present by extinguishing itself if an explosion risk is detected.
Chemical synthesis
Calcium carbide must be transported and stored safely in closed and airtight containers. Stable at room temperature but highly reactive with water and moisture generate extremely flammable acetylene gas. Pharmacies and manufacturers follow strict storage guidelines to prevent moisture contact and reduce explosion risks.
Calcium carbide typically remains stable when securely stored. There are some maintenance and repairs that users can do to themselves.
Avoid moisture
Avoiding moisture contact during use and storage prevents hazards. Users should regularly inspect containers for damage, moisture penetration, and signs of water contamination, including discoloration, rust formation, and unusual odors.
Proper containment
Using appropriate containers minimizes the risk of contamination. Ensure containers are airtight, made from materials resistant to corrosion, such as thick plastic or metal, and securely sealed after each use to protect from moisture and contaminants.
Monitoring acetylene production
Closely monitoring the water variable in acetylene production management prevents excess calcium carbide accumulation which is hazardous. Monitoring ammonia production, excessive acetylene production when combined with water usually produces an excess acetylene dangerous to handle. Monitoring is done by conducting regular tests. Mouth ammonia monitor ammonia levels in the acetylene. Tests are performed using simple litmus paper or ammonia detection.
Signs of acetylene contamination
Usually watch out for signs of acetylene contamination in produced acetylene gas. Unusual smells like garlic, burning, or chemical odors indicate contaminated acetylene. Other signs are black soot, difficulty igniting acetylene, and flames exhibiting irregular colors like yellow, orange, or blue instead of the usual white or pale blue.
Calcium carbide quality and safety maintenance during storage and handling increase end quality and reduce safety risks. This is how to handle it.
Purity requirements
Calcium carbide is typically 97% pure for industrial applications and 99% pure for chemical applications. Pure calcium carbide pellets usually produce more acetylene per reaction during water interaction.
Handling precaution
Storing and transporting calcium carbide in non-water reactive containers like metal or calcium plastic cells. When handling wear personal protective equipment like gloves, goggles, and face shields. Work areas should be well ventilated, free from open flames, sparks, and direct sunlight. Smoking near calcium carbide is extremely dangerous due to its high reactivity.
Reaction containment
Ensure water or moisture doesn’t contaminate calcium carbide since it reacts violently to produce acetylene. Store in airtight containers to prevent moisture entry, only opening containers when necessary and closing them securely afterward. Monitor for signs of contamination like container swelling, leaking, or discoloration and disposing of contaminated carbide safely according to local regulations.
Sourcing consideration
Buy from reputable suppliers who disclose complete product specifications. Ensure the supplier’s quality control procedures meet industry standards and supply certificates for acetylene, phosphorous, and impurities. A supplier’s grade usually matches application requirements, e.g., production grade for chemical processes and industrial grade for acetylene.
Emergency preparedness
Every business dealing with calcium carbide has emergency response plans for acetylene gas leakage, fire, or explosion. Fire extinguishers rated for flammable gas fires are always on standby, a clear evacuation route, and quick access to emergency services. Regular training on responding to acetylene leak and exposure instances is a good practice.
A1. Calcium carbide is made by heating limestone and coke at high temperatures in a furnace to separate the calcium and carbon elements. The separated elements react to form calcium carbide.
A2. The main use of calcium carbide is to produce acetylene gas by reacting it with water. Acetylene gas is used in welding, cutting metals, and as a ripening agent for fruits.
A3. Yes, calcium carbide is harmful when inhaled or ingested. It contains trace phosphine and arsenic which are extremely toxic. It can also cause skin burns and irritation upon contact.
A4. The product is widely banned in some countries based on its health hazard risk. Countries prioritizing public health and safety have banned it, especially fruit sellers.
