Pyrometallurgy 3 (Terms)

Question 1

• the oldest type of furnace
• the crucible is heated by the flame and radiation from the sidewalls, and transfers the heat to the bath
• the charge is isolated from external heat source

Answer 1

Oil/Coke-fired Crucible Furnaces

Question 2

• Uses heating coils
• Indirect heating of charge

Answer 2

Induction Furnace

Question 3

• the flame heats the bath both directly and by radiation from the roof
• considerable length is required to attain proper heat transfer from the long flame

Answer 3

Hearth Furnaces

Question 4

• electrodes deliver the electrical energy
• Electric arc + slag resistance provides heating
• advantages include
  ◦ high degree of
  temperature control,
  ◦ flexibility of operation,
  ◦ cleanliness of melt

Answer 4

Electric Arc Furnace

Question 5

• used for continuous melting
  processes;
• solid charge flows down under gravity and product collected at the bath
• Hot gases rise to heat / react with charge

Answer 5

Vertical Shaft Furnace

Question 6

recovery of volatile products

Answer 6

Retorts

Question 7

high temperature vessels in which gas is blown through liquid metal

Answer 7

Converters

Question 8

• Liquid product with the lowest specific gravity
• Generally the waste product
• Major components are oxides, fluorides, silicates, phosphates, borates, etc., but they lose their individual identities in the slag
• Complex, but single phase solutions

Answer 8

Slag

Question 9

Properties of Pyromet Phases

inherent porosities

Answer 9

Solid Metals

Question 10

Properties of Pyromet Phases

volatilize as mono-atomic gases; obey the IDEAL GAS EQUATION

Answer 10

Gaseous Metals

Question 11

Properties of Pyromet Phases

low viscosity, high surface tension, good solubility with other metals of similar characteristics

Answer 11

• Liquid Metals

Question 12

As the outlet of unwanted charge components, it must collect and dissolve the maximum possible amounts
◦ On the converse, it should carry the minimum amount of wanted component

Answer 12

• Metallurgical Requirements

Question 13

Fluxes are cost centers
◦ Sensible heat in slag
◦ Physical entrainment in slag

Answer 13

• Minimum Cost

Question 14

◦ Should not be too thick
o to resist flow out of the furnace
o to cause suspension of metallic phase

Answer 14

• Viscosity and Fluidity

Question 15

◦ The critical temperature of smelting systems are dictated by the temperature at which the slag forms and freely flows
◦ Presence of fluxes significantly lowers the melting temperatures of charge

Answer 15

• Formation and Free-Running Temperature

Question 16

◦ Should be compatible with the refractory of the furnace
◦ Acidic vs. basic slags

Answer 16

Corrosiveness

Question 17

◦ Should be significantly lighter than the metallic phase for ease of stratification

Answer 17

Specific Gravity

Question 18

 Balance between the amounts of silica, magnesia, quicklime, alumina, etc.
◦ E.g. steel refining – removal of sulfur and phosphorus

Answer 18

Acidic vs Basic Slag

Question 19

Basic slag tend to be ___

Answer 19

lumpy

Question 19

Acidic slag tend to be ___

Answer 19

viscous

Question 20

____Fe only exist when the sulfur is in excess relative to copper (stage converting of copper)

Answer 20

Fe

Question 20

Property of Matte

 When a metal forms more than one sulfide, the higher sulfide tends to ____ before melting, forming a lower sulfide and sulfur gas

Answer 20

decompose

Question 20

 Liquid solutions of sulfides
 Principal metallic products of copper and nickel smelting

Answer 20

Matte

Question 21

property of matte

At melting temp, the matte tends to volatilize ____

Answer 21

sulfur

Question 22

 Liquid solutions of arsenides and antimonides
 Hard to separate from the metal layer when formed
 Remedied by pre-roast / calcine prior to smelting

Answer 22

Speiss

Question 23

 Mixture of precipitated solid and liquid components
 Skimmed from the top of the metallic layer
◦ E.g. lead smelting

Answer 23

Dross