Pyrometallurgy 1 (terms) Flashcards
- The choice of extraction process is largely governed by
◦ type of ore
◦ chemical stability of the valuable minerals present - depends also on
◦ energy costs
◦ production rate
◦ required metal purity
Extractive Metallurgy
Selective reaction of valuable metal using aqueous reagents
Hydrometallurgy
electrolysis is used to selectively deposit the valuable metal
Electrometallurgy
heat is used to achieve decomposition of the valuable metal compound
Pyrometallurgy
The ________ has been predominant
◦ abundance and lower cost of fossil fuels
◦ stability at high production rates
pyrometallurgical method
(1____) are slower than pyrometallurgical methods but it is more suitable for dealing with (2________) ores
- Hydrometallurgical Methods
- Lean Ores
Involves the extraction or production of metals with chemical reactions at high temperature
Done on reactors w/ refractories
High temperature, non-aqueous reactions
Processes and techniques in refining ores with heat to:
◦ accelerate chemical reactions
◦ melt the metallic or non-metallic components
Extraction of metals using dry reagents
Pyrometallurgy
is applied to predict:
◦ whether a set of given reactions proceed or not
◦ The effect of changing the temperature in a course of a reaction
Thermodynamic Data
◦ Chemical reactions
◦ Change in state of
aggregation
Unit Processes
◦ No chemical reaction
◦ No changes in state
◦ Physical separations
only
Unit Operations
The relationship between quantities of all the elements and compounds coming in and going out of the process
Evaluated in terms of combining weights which are simple multiples of the atomic weights and its chemical analysis
Stoichiometry
Chemical reactions, changes in state, and simple temperature changes are accompanied by heat absorption or evolution
Evaluated based on data:
o Heats of formation, fusion
o Heats of reaction
o Specific heat
Thermochemistry / Thermophysics
Measurement of temperatures
o Flame
o Flue gas
o Refractory wall
o Molten phases
Pyrometry
Considers both the:
o quantity of heat supplied by the fuel
o temperature level at which fuel is supplied
Fuels and Combustion
Mechanisms of heat transfer
o Conduction
o Convection
o Radiation
Heat Flow
Mass transport phenomena
Focused on gas components of combustion
Fluid Dynamics
Physical and chemical changes of the solid charge and the liquid products, as a function of composition and temperature
Stability of phases at certain conditions
Phase Diagrams
Phase Equilibria
Control of which reaction can proceed, depending on temperature, pressure, and phase compositions
Equilibrium constants
Chemical Equilibria
Technologies appropriated for different processes
Brick wall structure and chemistry
Furnaces and Refractories
Rates of reactions
Rate of smelting, furnace throughput
Kinetics
process of heating the ore at a temperature not sufficient to melt the ore, in the absence of air
converts carbonate ores into oxides
Calcination Process
“separation by melting”
process of melting and separating the feed into two immiscible liquids
Smelting
Refining / purifying process
Converting
Solid impurities (metal oxides, metal sulfides, inorganic impurities), found floating on top of low melting temperature metals/alloys
Dross
Molten solution of oxides found on top of molten metal/matte
Slag
Unwanted, molten solution of arsenides of Fe, Co, Ni, Cu formed during matte smelting (located between matte and slag)
Speiss
Molten solution of sulfides formed during the smelting of Cu, Ni and Pb
Matte
Give data which are difficult, if not impossible, to obtain by direct measurement in a plant
Calculations on the input and output of all elements, metals, or compounds
Metallurgical Accounting
Stoichiometric Calculations
show the weights and analyses of input and output materials
Material Balance
The quantity of element is neither decreased nor increased by chemical or physical processes taking place in systems that contain the element
Basis: 1 Gram-Mole
Law of Conservation of Elements
When gases react, the volumes consumed and produced, measured at the same temperature and pressure, are in ratios of whole numbers
Law of Combining Volumes
Atoms combine to form molecules brought about by specific reactions involving the outermost electrons of the combining atoms
The relative weights can be expressed by the products of the atomic weights and small whole numbers
Principles of Combining Weight
unsa ni na law?
At constant temperature, the volume of a given mass of gas is inversely proportional to the pressure
Boyle’s Law
uno sini na law??
At constant pressure, the volume is proportional to the temperature
Charle’s Law
uno sini na law bayot
Observed that the fractional increase of the volume of gas of some gases are constant
Coefficient of Thermal Expansion (CTE) of Gases
Gay-Lussac’s Law
If α is equal to 1/273.15
◦ the fractional decrease in the volume of gas, per degree decrease in temperature, is 1/273.15 of the volume of gas at 00C
At -273.150C
◦ the volume of gas becomes zero, hence the limit of temperature decrease
absolute temperature
An ideal gas is defined as one in which all collisions between atoms or molecules are perfectly elastic and in which there are no intermolecular attractive forces
Ideal Gas Law
Standard Temperature and Pressure
Pressure:
1 atm
Standard Temperature and Pressure
Temperature:
0^0 c or 273 K
For Gases:
1 g-mol =
22.4 L
for gases
1 kg-mol =
22.4 m^3
for gases
1 lb-mol =
359 ft^3
Input=output
Steady State
Input = output + accumulation
Non-Steady State
most often used in stoichiometric calculations
o Given as tonnage per 24 hours
o Ideal Condition
Rate of Treatment
either maximum or nominal rate of treatment
Capacity
real time of residence in the reactor
(Mean) Retention Time
Used for metallurgical accounting
For minimizing losses
A table that shows the important elements in the input and output of a process
Metallurgical Balance
