4.2　Powder

4.2.1　The following powder may be used as reaction agent for pretreatment:

1　The mixture of lime powder and fluorite powder，or the mixture of passivated magnesium powder and lime powder，or the mixture of calcium carbide power and lime powder，or the mixture of calcium carbide powder and fluorite powder，or passivated magnesium powder，or calcium carbide powder may be used for desulfurization.

2　The mixture of lime powder，fluorite powder and iron oxide powder（scale，ore fines，fine sinter and dust from steelmaking equipment）may be used for dephosphorization and desiliconization.

4.2.2　The lime powder for the injection process shall be fluidized.

4.2.3　Sodium carbonate and other sodium-based desulfurizing powder that seriously pollute environment shall not be used as desulfurizing agent.

4.2.4　For calcium carbide，carbon powder and magnesium powder used as desulfurizing agent，the fire，explosion and moisture protection and other safety measures shall be provided for the storage，transport and use.

4.2.5　Desulfurizing agentshall be kept dry during storage.Passivated magnesium powder shall be stored under the protection of inert gas.

4.2.6　When passivated magnesium powder is transported to the production site in special bags，the desulfurizing agent bags may be transferred to elevated bin with crane.Other desulfurizing agents are transported to the shop by special tank cars and conveyed into powder bins with nitrogen.Alternatively，pneumatic transport may be adopted to directly convey desulfurizing agents to powder bins via pipeline from the powder preparation plant.

4.2.7　A dust collector shall be provided at top of powder bin.