The invention discloses a preparation method for low-
silicon, high-
calcium and large-
crystal fused magnesia. The preparation method comprises the following two steps: preparation of high-activity MgOand
smelting with an
electric arc furnace, i.e., during preparation of high-activity
magnesium oxide powder, adding a
sodium carbonate solution with a concentration of 3 to 8%, then adding high-puritygraphite
powder into the prepared high-activity
magnesium oxide powder as a
reducing agent, carrying out balling with a device, after balling is completed, carrying out
smelting with a fully-automatic
electric arc furnace, carrying out cooling and crystallizing, and carrying out crushing and picking so as to obtain a finished product. According to the invention, through addition of the
sodium carbonate solution, the point of melting is effectively reduced; the temperature of
calcination is reduced; and energy is saved. Meanwhile, through a reaction between
sodium carbonate with
silicon dioxide impurities,
sodium silicate and
carbon dioxide can be generated; the
silicon dioxide impurities in
magnesite can be effectively removed; and the content of
magnesium oxide is improved. The low-silicon, high-
calcium and large-
crystal fused magnesia provided by the invention reaches an MgO content of 99.90% or above, achieves a
calcium-to-silicon ratio of 2.30 or above, has good high-temperature
fire resistance and high-temperature scouring resistance, and can be used as a high-quality advanced
refractory material to be applied in the industries of
aerospace,
electronics, steel and iron,
metallurgy, etc.