Pyrometallurgy 2 (terms)

Question 1

• Statement of the energy balance of a given system
  o It is less abstract than the formal thermodynamic treatment
  o It accounts for the input and output
  o Based on the 1st Law of Thermodynamics

Answer 1

Metallurgical Heat Balance

Question 2

Items in a Heat Balance

◦ Heats of reaction (exothermic reactions)
◦ External heat supply

Answer 2

 Input terms

Question 3

Items in a Heat Balance

◦ Heat absorbed by endothermic reactions
◦ Heat absorbed in bringing input materials to the reference temperature
◦ Heat loss to surroundings

Answer 3

Output terms

Question 4

 Supply the necessary amount of heat to attain the satisfactory temperature level

Answer 4

Heat Utilization

Question 5

associated with any change of state in a material is a change in the heat content of the system
◦ Exothermic Reaction

Answer 5

Chemical Energy

Question 6

maybe solid, liquid or gaseous
*liquid fuels: petroleum, oil, alcohol
*gaseous fuels: natural gas
*solid fuels are: coal and coke
*mined from tar sands and oil shale and methane hydrates
*further requires distillation and upgrading to produce crude and petroleum

Answer 6

Hydrocarbon Fuels

Question 7

◦ advantage is that there is no contamination of the charge by the fuel

Answer 7

Electricity

Question 8

◦ energy which has been produced in another part of the plant and recycled within the plant
◦ Heat exchangers, flue gases

Answer 8

Conserved Heat

Question 9

Heat Utilization

◦ the temperature required to carry chemical reaction effectively
◦ For processes producing a slag, it is the minimum temperature with which slag flow is achieved

Answer 9

Critical Process Temperature

Question 10

Heat Utilization

◦ the maximum temperature theoretically attainable assuming complete combustion of fuel under adiabatic conditions
◦ The temperature of the combustion products when the reaction is carried out without any loss of heat

Answer 10

Adiabatic Flame Temperature (AFT)

Question 11

◦ the total input from the combustion of fuel, less the sensible heat in the combustion products at the critical temperature
◦ the heat given up by the combustion products to the furnace and its contents when cooled from AFT to critical temperature
◦ proportional to (TAFT – T crit)
◦ anything that increases the AFT also increases the gross available heat

Answer 11

Gross Availability Heat

Question 12

◦ the gross available heat less the net losses in the furnace
Smelting Power:
◦ the maximum furnace throughput
◦ net available heat generated per unit time divided by the net required available heat per unit throughput

Answer 12

Net Availability Heat

Question 13

◦ sensible heat from flue gas represents considerable amount of fuel cost, and any heat recovered would improve the profitability of a given process
Uses of recovered heat:
◦ preheat of combustion gases/fuel
◦ conversion to steam power
◦ drying of ore

Answer 13

Heat Recovery from Flue Gas

Question 14

rate of heat flow and temperature at any position does not vary with time

Answer 14

Steady State

Question 14

continuous type, wherein both fluids are flowing continuously through the system being separated only by walls through which heat transfer occurs

Answer 14

Heat Recuperators

Question 15

contain heat storage elements which alternately absorb heat from the flue gas and then give up heat to the cold air being preheated

Answer 15

Heat Regenerators

Question 16

rate of heat flow and temperature at any position vary with time

Answer 16

Unsteady State

Question 17

heat flow through a body without displacement of particles in the body; heat flows in a stationary medium

Answer 17

Conduction

Question 18

heat flow through a body which involves displacement of particles; heat flows in liquid and gases

Answer 18

Convection

Question 19

heat flows in vacuum

Answer 19

Radiation

Question 20

Uno sini na law?

◦Rate of heat flow is proportional to the difference in temperature

Answer 20

Fourier’s Law

Question 21

◦ Constant cross-sectional area ⊥ to the direction of heat flow
◦ One (1) dimension &laquo_space;other two (2) dimensions
Neglect end effects

Answer 21

Slabs

Question 22

◦ Cross-sectional area changes with position
◦ Heat transfer through r and θ

Answer 22

Cylinders

Question 23

◦ Molecules are agitated
◦ Atoms easily collide with neighboring atoms to the right
◦ Process continues until all molecules transfer their kinetic energy to those in the cold wall

Answer 23

Hot Wall

Question 23

◦ Three (3) directions of heat flow

Answer 23

Spheres

Question 24

 Material property
 Expresses the amount of heat a material can transmit at a given time as a consequence of a thermal difference
 Speed of heat transfer from point A to B through lattice vibrations

Answer 24

Thermal Conductivity

Question 25

Tempreature is at the same at the interface

Answer 25

Composite Slab