De-ashing of coal by combined jig washing, froth-flotation, and extraction with caustic soda

Technical Report · Tue Jan 01 04:00:00 EST 1946

OSTI ID:7176225

Crawford, A

Pitch coke or petroleum coke was used for the manufacture of carbon electrodes in the electrolytic smelting of aluminum from bauxite. A number of processes were developed to obtain a substitute for them from coal. The purity of the carbon forming the electrodes, particularly the anode, was very important, so a first essential in the use of coal was its freedom from mineral matter and other impurities. The processes were used for that purpose and could be used for some other purposes are discussed. Coking coal of 22% volatile content and 12.5 mm in size was cleaned in a first stage of jig washing to 4% to 5% ash. This stage is considered in more detail and a figure shows the different views and sizes of different parts of jig washing. The cleaned coking coal with 4% to 5% ash was creamed in a second stage of jig washing to 1.8% ash, then ground finely and froth floated to .8% ash. Th reduce the size of the particles, two coarse crushers and six Teutonia disc mills were operated in the froth-flotation process. As well as providing low-ash coal, the froth flotation treatment was described as having the advantage of removing iron compounds. One figure and some numerical results are given about this process. Finally the low-ash coal was extracted with caustic soda at an effective concentration of 2.5% for 20 minutes at 120 atm pressure and 250/sup 0/C. It appeared essential to employ an acid-washing stage since the removal of caustic alkali by numerous washes with water alone proved impossible. If acid was not employed, the final result was an alkali-activated coke. The product in this process was both acid- and water-washed and contained 10% moisture and 0.28% ash. A table presents information on the effect of treatment on coal and coal ash and it appeared that the extraction process destroyed at least half of the caking properties of a good coking coal. Also information about costs are given. 3 tables, 3 figures

• Research Organization: Texas A and M Univ., College Station (USA)
• OSTI ID: 7176225
• Report Number(s): TOM-226-656-672
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010401 -- Coal & Coal Products-- Carbonization-- (-1987)
010402 -- Coal
Lignite
& Peat-- Purification & Upgrading
010600 -- Coal
Lignite
& Peat-- Properties & Composition
013000* -- Coal
Lignite
& Peat-- Transport
Handling
& Storage
ALKALI METAL COMPOUNDS
ANODES
ASHES
CARBONACEOUS MATERIALS
CARBONIZATION
CENTRIFUGATION
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
CLEANING
COAL
COAL PREPARATION
COAL PREPARATION PLANTS
COKE
COKING
COMMINUTION
CONTROL EQUIPMENT
COST
CRUSHING
DATA COMPILATION
DEASHING
DECOMPOSITION
DESIGN
DIAGRAMS
ELECTRIC POWER
ELECTRODES
ENERGY SOURCES
EQUIPMENT
EXTRACTION
FILTERS
FILTRATION
FLOTATION
FLOW REGULATORS
FOSSIL FUELS
FUELS
HIGH PRESSURE
HIGH TEMPERATURE
HYDROGEN COMPOUNDS
HYDROXIDES
INDUSTRIAL PLANTS
INFORMATION
INORGANIC ACIDS
MEDIUM TEMPERATURE
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PIPES
POWER
PROCESSING
PUMPS
PURIFICATION
REMOVAL
RESIDUES
SEPARATION PROCESSES
SIZE
SODIUM COMPOUNDS
SODIUM HYDROXIDES
TABLES
VALVES
WASHING
WATER