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LegendNewfound land1. Great Bend (rnagnesite)2. Port-au-port (dolomite)Nova Sco t i a3. Meat Cove (brucite)4. Cape Breton (dolomite)New Brunswick

5. St. John City (dolomite)Quebec6. Kilrnar (rnagnesite)7. Wakefield (brucite)8. Harve St-Pierre (dolomite)9. Ferrnont (dolomite)Ontario10. Deloro (rnagnesite)11. Rutherglen (brucite)12. Haley (dolomite)13. Guelph (doornite)Mani toba14. lskwasurn Lake (rnagnesite)15. Winnipeg (dolomite)

Saske tchewan16. Arnisk Lake (rnagnesite, dolomite)Br i t i sh Co lumbia17. Mo unt Brussilof (rnagnesite)

Fig. 1 - rincipal dep osits and occurrences of rnagne site, brucite and dolomite in Canada. FairrnOnt

Magn esite flotation collectors were generally the fatty Flotation was successful in concentrating a low-gradeacid type. Various derivatives were emp loye d between bruci te ore from Farm Point , Ontario (B ennett , 1941).ApH 9.1 and 1 0.3 with concentration levels between 100 brucite concentrate analyzing 88.2% MgO after calcina-and 92 0 g/t ( 3.5 and 32.4 oz/st) on ore sizes less than2 10 tion, and containing very little calcite, was obtained frompm ( 70 me sh ) . Sodium si l icate and quebracho were 3 1% brucite feed material. The brucite was floated usingemployed as depressants. Sodium si l icate (700 to 2000 g/ a higher aliphatic secondary alcohol sulfate after grindingt or 25 to 7 1 oz/st ) was used fo r slime dispersion, and also to -300 pm (-50 mesh) and desl iming at 60 jlm (230 mesh).

to depress quartz and calcite . Quebrac ho (500 to 16 00 g/ Modifiers included sodium silicate as a slime dispersantt o r 18 to 56 oz/st) w as used to depress calcite. and quartz depressant and tannic acid as calcite depres-

The concentration of magnesite by heavy media sepa- sant.ration and wet and dry gravity concentration method s was Photom etric sorting was used to remove serpentine andbased on differences in specific gravity between m agnes- dark-colored silicate minerals in a study of brucite oreite and gangue minerals. In one study of magnes ite from from Wakefield, Quebec (Wyman, 1968). In anotherKilmar. Quebec (Johnson,1942), heavy media separation study of brucite ore from Wak efield, Quebec (Zoldners,was used to separate magnesite (specific gravity 3.00) 1962 ),sized brucite was successfully evaluated as asou rcefrom dolomite (spec fic gravity 2.85) and serpentine (spe- of coarse aggregate for use in concrete.cific gravity 2.55). The separation of rnagnesite frombrucite (sp ecific gravity 2.39) was attempted by air tabling Dolomite benef icia t ion

and wet tabl ing of +420 p m (40 mesh) material. In eachcase, a 90% magnesi te grade was achieved from 65% Dolom ite beneficiation was more straightforwa rd thanmagnesi te feed grade (Wym an, 195 8). that of mag nesite and brucite. It only involved dry pro-

Magn etic separation as a secondary bene ficiation tech- cessing. Technique s studied included screening, air clas-nique was successful in various studies for removing sification and photome tric sorting. Calcination evalua-liberated magnetic material from concentrated magnesite tion was either for dolomitic lime or as refractory rawflotation concentrates. It was less successful, however, in material.removing iron locked in the magnesite crystal lattice. Dolomite ore from Haley, Ontario was evaluated inPhotometr ic sort ing of magnesi te ore from Kilmar, Que- three separate studies:bec was partially successful in separating magnesite fromserpentine (Wyman. 1973). Air classification successfully separated a -75 ym

(-200 mesh) fract ion (W yman, 1963).Bru c i t e b en ef i c i a t i o n Photometric sorting successfully produced a very

white -12.5 +4.8 mm (-0.5 in. + 4 mesh) fractionProcessing b rucite was very sim ilar to magne site, that

(Wyman. 1966).is, beneficiation to produce a brucite concentrate followed A third sample was successfully evaluated ass refrac-by calcination for refractory use evaluation. Beneficiation tory raw material and as a furnace-fettling compoundtechniques included screening, flotation and photometric using iron oxide as the fluxing agent (Palfreyman.sort ing. 1974).

MINING ENGINEERING MARCH 1994 235

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