Metallurgical Transactions B

, Volume 13, Issue 4, pp 581–588

Vacuum distillation of liquid metals: Part I. Theory and experimental study

  • R. Harris
  • W. G. Davenport
Pyrometallurgy

DOI: 10.1007/BF02650015

Cite this article as:
Harris, R. & Davenport, W.G. MTB (1982) 13: 581. doi:10.1007/BF02650015

Abstract

The kinetics of vacuum distilling copper, tin, manganese, and sulfur from melted steel scrap have been measured. The experiments found that 70 to 90 pct of initial copper, 60 to 80 pct of initial tin, 80 to 100 pct of initial managanese, and 20 to 40 pct of initial sulfur can be eliminated in 30 minutes exposure to vacuum. Melt masses were in the range 10 to 60 kg, melt temperatures in the range 1850 to 2050 K, and chamber pressures in the range 3 to 400 pascals. Crucible diameter was 0.2m. Mass transport has been described in terms of Machlin's model for melt phase diffusion, Langmuir's model for evaporation, and convective bulk flow for gas phase mass transport. Two preliminary criteria are shown to demonstrate the suitability of vacuum distillation to any particular system and a third operational criterion is developed to define the range of vacuum required to eliminate gas phase mass transport resistance effectively.

List of symbols

A

melt surface area exposed to vacuum m2

c

molar concentration kg-mole m−3

Dil

diffusion coefficient in liquid m2s−1

Dig

diffusion coefficient in gas phase m2s−1

h

melt depht m

K1

liquid phase rate coefficient ms−1

K2

evaporation rate coefficient ms−1

K3

gas phase rate coefficient ms−1

M

molar mass kg kg-mole−1

N

mole fraction

n

molar flux kg-mole m−2s−1

P

pressure pascal

Po

equilibrium vapor pressure pascal

R

gas constant joules kg-mole−1 K−1

rl

melt radius m

T

temperature K

V

melt volume m3

vt

melt surface velocity ms−1

vg

bulk gas velocity ms−1

Z

total number of species in solution

Greek symbols

γ

Raoultian activity coefficient

ρ

density of melt kg m−3

ϕ

multiplier which relates vapor pressure to molar concentration pascal m3 kg-mole−1

Subscripts

b

bulk

bp

back pressure

ch

chamber

g

gas phase

i

species i

l

liquid phase

s

surface

x

coordinate

Copyright information

© American society for metals and the metallurgical society of Aime 1982

Authors and Affiliations

  • R. Harris
    • 1
  • W. G. Davenport
    • 2
  1. 1.Department of Metallurgical EngineeringMcGill UniversityMontrealCanada
  2. 2.Department of Mines and MetallurgyUniversity of ArizontaTucson

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