MODELLING OF THE GRANULATION OF POWDER TITANIUM MAGNETITE CONCENTRATE AND ITS REDUCTION WITH NATURAL GAS
The granulation of titanium magnetite concentrate containing up to Fe- mass fraction 54%, TiO2- 7%, V- and 1% Mn – 0.8%, with 25% mass fraction fluxing additives soda has been modelled. The process of granulation and direct reduction of titanium magnetite concentrate with natural gas in the filter layer of tube furnace to obtain the iron powder and titanium fraction have been modelled. The construction of a complex model of titanium magnetite granule formation of powdered materials in drum granulators taking into account the anisotropy the structure and laminating on the surface is considered. It has been noted that granule formation proceeds in some stages depending on the relaxation time of embryo formation. Based on this model a graphic interpretation of the process laminating powder on the surface is cited. The rheological model of the compaction of granules under the action of external deformation stresses allows estimate the change of porosity and density is presented. The comparison of calculation and experimental results for the evolution of the distribution of granules on the sizes has been presented. The temperature dependence of the Gibbs free energy of reduction reactions was calculated.
The dependence of metallization degree (μ,%,mass fraction) of fluxed (25% Na2CO3) pellets of titanium magnetite concentrate on the natural gas recovery temperature during the recovery duration, t = 30 min., flow rate of natural gas ν = 0.1 l/min and the amount of natural gas for recovery V = 0.6 m3/kg is approximated with the polynomial μ = 14.933.10-6T3 – 0.043T2 + 41.222T – 13042.
The dependence of metallization degree of the fluxed pellets of titan-magnetite concentrate of sandstones on recovery duration (t) with natural gas at 900 °C, flow rate of natural gas u = 0.1 l/min and amount of natural gas for recovery V = 0.6 m3/kg is approximated with the polynomial μ = – 0.2417 ∙ 10-4 t4 + 0.0041t3 – 0.2508t2 + 6.6263t + 35.
Thus, to recover pellets of titanium magnetite concentrate with natural gas in the filter bed of the horizontal reactor of a laboratory tube furnace when using fluxed pellets of 3 – 7 mm the following optimal conditions were established: T = 875 ÷ 925° C, process duration τ – 30 minutes, natural gas rate – 0.1 l/min. and at gas amount – 0.6m3/kg. Under these conditions the metallization degree of fluxed pellets of titanium magnetite concentrate reaches 97- 98.5% and the carbonization, caking and sintering of recovered pellets is avoided.
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