I think submerged arc furnace smelting depends on two factors: process characteristics and parameter selection.
Process characteristics-According to the resistance characteristics of the smelting melt, select the appropriate smelting mode.
Parameter selection-according to process characteristics, flexible selection of appropriate electrical parameters.
Speaking of smelting modes, briefly introduce the three major smelting modes of submerged arc furnace.
Submerged arc mode-submerged arc and hot furnace mouth operation that requires energy to be released from the slag layer, such as high-carbon ferrochrome, silico-manganese alloy.
Submerged arc mode-requires energy to be concentrated in the submerged arc and cold material surface operation in the reaction zone (note: different from the above), such as: ferrosilicon.
Resistance mode-such as: tungsten iron smelting.
Arc shielding mode-requires energy to be released on the surface of the molten pool and hot furnace mouth operations, such as nickel-iron.
1. Submerged arc mode-laterite ore-melt resistance characteristics (with limestone)-slag type (silica-calcium oxide-magnesium oxide, alkalinity is about 0.93)-ferronickel products (nickel group Low content, high iron content, containing 10%-11% nickel)
Electrical parameters-high current, low voltage-low power factor-easy to insert electrodes-easy to cut off or under load-high smelting temperature (average above 2100 degrees)-serious corrosion of furnace bottom- High power consumption
2. Arc shielding mode-laterite ore-melt resistance characteristics (natural ore)-slag type (ferrous oxide-silica-magnesia system, alkalinity about 0.6)-ferronickel products (nickel component High, low iron content, containing 15%-20% nickel)
Electrical parameters-low current, high voltage-high power factor-electrode lift-low smelting temperature (melting slag is 1623-1703 degrees, alloy melting point is 1400-1493 degrees)-low power consumption
Through the comparison of the process and electrical parameters of the above two modes, it can be seen that the submerged arc mode furnace is deteriorated, difficult to operate, low in nickel content, and high power consumption; while the shielded arc mode has great advantages, and the furnace condition is stable and easy to operate. Operation, high nickel content, low power consumption.
This is the conclusion drawn by the production test of the smelter, not the result of imagination.
Therefore, the shielded arc mode is the preferred mode for most submerged arc furnaces (that is, Elkem method) smelting ferronickel at home and abroad.