Characteristics and transportation risks of silicon-related goods

There are various types of silicon-related goods and complex nature, including both dangerous goods and general goods. The common silicon slag, silicon mud, and other silicon-related goods in the transportation link, although they have a certain fire hazard, are not included in the "International Maritime Dangerous Goods Regulations" and "Dangerous Goods List" or have special regulations in them. Therefore, the transportation is carried out as ordinary goods, which poses a great safety hazard.

Common silicon-related goods in waterway transportation include silicon slag, silicon slag balls, silicon mud, and silicon carbon balls. Silicon slag is a by-product of the process of smelting silicon. It contains a certain amount of free silicon and silicon carbide. It can be used as a raw material for smelting cast iron and silico-manganese alloys, and it can also replace silicon powder as a deoxidizer for steelmaking. The silicon slag ball is a ball made by adding a small amount of corn starch and water to the silicon slag and mixing it evenly. The silicon content is generally 20% to 65%. Silica sludge is an industrial waste produced during the production of silicon wafers from monocrystalline silicon or polycrystalline silicon rods using the diamond wire cutting process. It is usually used as general industrial solid waste. It is a gray-black brittle lump or powder with a water content of 40%~ 60%, the main ingredients are silicon, silicon dioxide, filter aids, surfactants in cutting fluids, organic acids, etc. Silicon-carbon balls are made of a variety of alloy powders (silicon powder, graphite powder, etc.) and an appropriate amount of active agent in a certain proportion. They are mainly used in steelmaking and foundry industries.

Two forms of bulk and packaging are commonly used in the transportation of silicon-related goods. Silicon slag and silicon sludge are generally transported in bulk, while silicon slag balls and silicon-carbon balls are generally transported in bags or containers. During transportation, the concentrated accumulation of a large amount of silicon slag and silicon sludge may cause the internal temperature to rise, and the heat cannot be dissipated, which may cause spontaneous combustion.

Case:

At 22:07 on April 19, 2021, the “China Fuqiang” passenger ship with the largest passenger capacity in Asia and a rated passenger capacity of 2,262 (the actual voyage of 677 passengers) was operated and managed by China Weihai Haida Passenger Transport Co., Ltd. On the ro-ro cargo ship, smoke was emitted from the truck in the vehicle cabin on the way from Weihai to Dalian. The ship hurried back to Weihai Port and deflagrated during the subsequent emergency rescue process. Fortunately, the evacuation of the people on the ship did not cause casualties in time. It is preliminarily determined that the accident was caused by the spontaneous combustion of the silicon mud carried by a truck on the ship.

In addition, some related to silicon goods (silicon aluminum powder, ferrosilicon) in water or moisture will release flammable gas (hydrogen, etc.) and toxic gas, flammable gas, and air mixture to form an explosive gas mixture, ignition source will occur combustion or explosion. Therefore, for the fire of silicon-related cargo, if an incompatible and unsuitable fire-extinguishing medium is used or the wrong fire extinguishing method is adopted, the fire extinguishing time will be delayed at a light level, and the consequences of the accident will be greater at a serious level.

Generally speaking, silica slag, silica mud and other silicon-related goods transported as general goods have the fire danger characteristics such as spontaneous combustion and flammable gas release when water meets certain conditions, and emergency disposal after a fire is demanding and difficult. Therefore, in view of the frequent occurrence of silicon-related cargo accidents in transportation in recent years, we should attach great importance to the risk prevention and control of silicon-related general cargo with fire risk in transportation while paying attention to silicon-related dangerous cargo.

The above information comes from the "World Shipping" article "Attention! This kind of goods is not listed as "dangerous goods", but it has caused many fires and deflagration accidents." Author Zhu Jianhua, Li Xuedong, etc.