Modelling of fluid flow and kinetics in counter-current reactors for pyrometallurgical refining

<p>“Results of physical modelling and kinetic (mass transfer) simulation of a counter-current reaction launder (CCRL) for metals refining are presented. Physical modelling was conducted in a 200 cm long (L) by 20 cm wide (W) channel, using tetrachlorethylene to model 'metal' and water to model 'slag'. A thermal tracer technique was used to measure the eddy thermal diffusivity ( α_e) and the interphase heat transfer coefficient (h_ov). The heat and mass transfer analogy was then applied to determine the extent of longitudinal mixing (D_e/uL) and to estimate the rate of interphase mass transport (k_ov). Liquid 'metal' height (H₁) was kept constant at 20 cm, while the liquid 'slag' height (H_u) was varied between 5 and 18 cm. Nitrogen was bottom injected at a rate per unit area of 7.5 cm/min, through up to 16 central bubblers placed along the length of the CCRL. Low extents of longitudinal mixing in the 'metal' of D_e/uL less than 0.1 were measured. Interphase mass transfer coefficients of the order of 0.004 cm/s were estimated from the measured interphase heat transfer coefficient (h_ov = 1.3 to 2.0 kW/mK). Interphase heat transport was found to be a strong function of the gas stirring energy input (∈), according to h_ov ∞∈ ^0.63, provided H₁/W and H₁/H_u met, or exceeded unity.</p> <p>Kinetic simulation was applied to prediction of the performance of a novel CCRL process for production of low carbon ferromanganese (LC FeMn). A dimensionless (N_CCRL)_s = (kAp/m)_s of 1.8 in the slag was predicted to yield highly refined LC FeMn (0.70 % Si), at a 97 % silicon utilization efficiency, and with a 89 % recovery of manganese to the alloy. A transitory reaction, tanks-in-series kinetic model was used to investigate nitrogen absorption and desorption. Substitution of argon for nitrogen was predicted to reduce the liquid LC FeMn nitrogen content from 0.98 to 0.025 % N, but at an estimated additional operating cost of about $10 /t LC FeMn”--Abstract, page iv.</p>

Name thesis:degree_name

Ph. D. in Metallurgical Engineering

Grantor

University of Missouri--Rolla

Year dc:date.available

2016

Author dc:creator

• Nelson, Lloyd R.

• Metallurgy

Repository record dc:identifier

https://scholarsmine.mst.edu/doctoral_dissertations/1078

OAI identifier oai:identifier

oai:scholarsmine.mst.edu:doctoral_dissertations-2080