Patent GB-1059476-A (GB)
Title: Ore treating process
IPC: C22B1/00
Filed: 1964-06-10
Abstract: A process for treating tin oxide containing ores comprises (1) sulphidizing tin oxide in the ore by heating the ore with sulphur in gaseous form in a non-oxidizing atmosphere for a time sufficient to convert at least part of the tin oxide to tin sulphide as a superficial surface coating on the ore particles, (2) cooling the ore under non-oxidizing conditions, and (3) subjecting the artificial tin sulphide ore thereby obtained to concentration by flotation at pH 3.7 to 4.5, the sulphide concentration then being recovered.  The ore may be cassiterite Bolivian tin ore, and may be crushed before sulphidization. The gaseous sulphur may be generated by heating elemental sulphur above 444 DEG  C. or by heating a sulphur compound such as iron pyrites, marcasite, hydrogen sulphide to decompose it, or by heating the ore if the latter contain impurities such as sulphur, iron pyrites or other metal sulphides.  Suitable non-oxidizing atmospheres include nitrogen, carbon dioxide, hydrogen, methane, carbon monoxide, natural gas.  Where the atmosphere is a combustible gas, it may be flamed at the mouth of the sulphidizing furnace to effect a seal against air. The sulphidized ore is cooled in a non-oxidizing atmosphere or quenched or otherwise cooled so as to avoid re-oxidation.  The ore may be sulphidized in a horizontal or vertical tube or rotating drum.  The ore may then be ground, suspended in water and flotation reagents added. Flotation reagents mentioned comprise: collectors such as potassium or sodium alkyl xanthates and other sulfhydryl types of collectors, soaps, together with hydrocarbons such as kerosene; frothing agents such as crude cresylic acid, higher alcohols, e.g. amyl alcohols and steam-distilled pine oil; pH modifiers such as soda ash, sodium hydroxide, lime and sulphuric acid; depressants such as alkali cyanides, starches, sulphites, zinc sulphate, chromates; dispersants such as sodium silicates and lignin sulphates; activators.  The concentrate may be reground, retreated, filtered, roasted or handled again by flotation with reagents to obtain the optimum grade of concentrate.ALSO:A process for separating tin sulphide from sulphidized tin oxide-containing ores comprises (1) sulphidizing tin oxide in the ore by heating the ore with sulphur in gaseous form in a non-oxidizing atmosphere for a time sufficient to convert at least part of the tin oxide to tin sulphide as a superficial surface coating on the ore particles (2) cooling the ore under non-oxidizing conditions and (3) subjecting the artificial tin sulphide ore thereby obtained to concentration by flotation at pH 3.7 to 4.5, the sulphide concentration then being recovered.  The ore may be cassiterite Bolivian tin ore, and may crushed before sulphidization.  The gaseous sulphur may be generated by heating elemental sulphur above 444 DEG C or by heating a sulphur compound such as iron pyrites, marcasite, hydrogen sulphide to decompose it, or by heating the ore if the latter contain impurities such as sulphur, iron pyrites or other metal sulphides.  Suitable non-oxidizing atmospheres include nitrogen, carbon dioxide, hydrogen, methane, carbon monoxide, natural gas.  Where the atmosphere is a combustible gas, it may be flamed at the mouth of the sulphidizing furnace to effect a seal against air. The sulphidized ore is cooled in a non-oxidizing atmosphere or quenched or otherwise cooled so as to avoid reoxidization.  The ore may be sulphidized in a horizontal or vertical tube or rotating drum. The ore may then be ground, suspended in water and flotation reagents added.  Flotation reagents mentioned comprise: collectors such as potassium or sodium alkyl xanthates and other sulfhydryl types of collectors, soaps, together with hydrocarbons such as kerosene; frothing agents such as crude cresylic acid, higher alcohols e.g. amyl alcohols and steam distilled pine oil; pH modifiers such as soda ash, sodium hydroxide, lime and sulphuric acid; depressants such as alkali cyanides, starches, sulphites, zinc sulphate, chromates, dispersants such as sodium silicates and lignin sulphates; activators.  The concentrate may be reground, retreated, filtered, roasted or handled again by flotation with reagents to obtain the optimum grade of concentrate.