Calcium carbide is commonly known as calcium carbide. Industrial stuff comes in gray, yellowish-brown, or black. If there’s a lot of calcium carbide, it might even look purple. When you cut it, it’s shiny at first, but it soaks up moisture from the air and then turns gray or off-white. It is electrically conductive, with higher purity yielding better conductivity. It absorbs moisture in the air. When added to water, it decomposes into acetylene and calcium hydroxide. It reacts with nitrogen to form calcium cyanamide. Calcium carbide is one of the basic raw materials in the organic synthetic chemical industry and a key raw material in the acetylene chemical industry. Acetylene produced from calcium carbide is widely used in metal welding and cutting.
There are two production methods: aerobic heating and electrothermal. The electrothermal method is generally used to produce calcium carbide. Quicklime and carbon-containing raw materials (coke, anthracite, or petroleum coke) are placed in a calcium carbide furnace, where they undergo a high-temperature melting reaction using an electric arc to produce calcium carbide. The production process is shown in the figure. Here’s how our production process works: First, we prep the raw materials. Then, we measure and mix them. Next, we put the mix into a furnace using an opening or pipe up top. Inside, we heat it to about 2000℃ in either an open or closed furnace.
The molten calcium carbide is removed from the furnace bottom, cooled, crushed, and packaged as finished products. The carbon monoxide produced during the reaction is discharged in different ways depending on the type of calcium carbide furnace. In open furnaces, the carbon monoxide burns on the charge surface, with the resulting flames dispersing along with the dust. In semi-closed furnaces, some of the carbon monoxide is extracted by an exhaust hood mounted above the furnace, while the remainder remains burned on the charge surface. In closed furnaces, all of the carbon monoxide is extracted.
Calcium Carbide Production Process
After being crushed and screened, the burned lime is stored in a lime silo until ready for use. Lime and coke meeting the production requirements are mixed in the specified ratio. Bucket elevators transport the charge to the furnace’s roof hopper, where it is fed into the furnace through a feed pipe. Inside the furnace, the charge reacts with the arc pads and the charge to produce calcium carbide. The calcium carbide is periodically removed from the furnace and placed in a calcium carbide pot. After cooling, it is crushed to the required particle size to produce finished calcium carbide. In the calcium carbide furnace, the heat generated by the arc and resistance heats the charge to 1900-2200℃.
Calcium Carbide Furnace Production Process
Batching, Loading, and Top-Load Distribution
Qualified raw materials are metered and batched in the raw material processing workshop. They are then transported by bucket elevator to the furnace’s hopper. The top-loading facility, fixed belt conveyor, and ring-type distributor deliver the material to the top-loading ring hopper. The top-loading system sends the charge into the hopper bit by bit. From there, it goes into the furnace through the feeding pipe in batches.
Electric Furnace
The semi-enclosed calcium carbide furnace, consisting of a furnace body, furnace cover, electrode holder, electrode pressing and releasing mechanism, and electrode lifting and lowering mechanism, is the core equipment for calcium carbide production. Powered by a transformer, the charge reacts within the furnace to produce calcium carbide through a high-temperature reaction, releasing carbon monoxide gas. The resulting calcium carbide is discharged through the furnace outlet. A burn-through device opens the furnace outlet, allowing the molten calcium carbide to flow into the calcium carbide pot on the cooling trolley. The electrode’s pressing and lowering are managed by a hydraulic system. It uses a cylinder to clamp and lift the electrode. A cone-shaped ring cylinder squeezes the conductive jaws. Usually, three winches on the fourth floor control the electrode’s up and down movement. All electrode actions—lifting, pressing, lowering, clamping, and releasing—are controlled with buttons in the operating room on the second floor. Powered by a transformer, the charge reacts within the furnace to produce calcium carbide through a high-temperature reaction, releasing carbon monoxide gas. The resulting calcium carbide is discharged through the furnace outlet. A burn-through device opens the furnace outlet, allowing the molten calcium carbide to flow into the calcium carbide pot on the cooling trolley. The exit furnace has a screen and arc drilling frame. To remove fumes made when unloading, there’s a fume hood over the furnace outlet that’s connected to a ventilator.
Electric Furnace Cooling, Crushing, and Packaging
Molten calcium carbide is taken from the pot using a lifter and moved to the corridor or packaging room to cool down. Once it hardens, a bridge crane with single-clamp clamps lifts it out and puts it on the cast iron floor until it’s cool. After cooling to a moderate temperature, the carbide is crushed to a desired particle size, graded, packaged, and sent to the finished product warehouse.
