US665744A - Process of treating sulfid ores. - Google Patents

Description

NITED STATES PATENT Fries.

HUGH FITZALIS KIRKPATRICK-PICARD, OF LONDON, ENGLAND.

PROCESS OF TREATING SULFID ORES.

SPECIFICATION forming part of Letters Patent No. 665,744, dated January 8, 1901.

Application filed June 28, 1900. Serial No. 21,988. (Specimens) To all whom it may concern:

Be it known that I, HUGH FITZALIS KIRK- PATRIOK-PICARD, a subject of the Queen of England, residing at London, England, have invented a certain new and useful Process of Treating Sulfid Ores, (for which I have made application for Letters Patent under No. 2,151, dated February 2, 1900,) of which the following is a specification.

This invention has for its object the treatment of what are commonly known as complex sulfid ores-t. 6., those containing as chief constituents zinc, lead, gold, silver, and sulfur-of which type of ores the Broken Hill sulfid ores are good examples.

The novelty of my invention consists in the manner in which these known reactions are practically applied to smelting these complex ores,whereby commercially successful results are obtained.

My process is briefly described as follows: The ore is first finely ground in any suitable mill and is then submitted to an oxidizing roast in a reverberatory furnace with the object of producing the maximum amount of oxids of lead and zinc and the minimum amount of sulfates. The sulfurous gases produced during the roast may be collected and utilized in any of the ordinary well-known ways. Inasmuch as it is impossible in ordinary roasting practice to entirely convert all the lead sulfid present to lead oxid means must be taken to reduce to a minimum the amount of sulfate produced, and I find it useful after the first stage of roasting is finished, with the object of getting the oreas far as possible in the form of oxids, to mix a small amount of coal-slack or other carbonaceous material with the roasted charge while still in the furnace and to reheat the mixture for the further decomposition of such sulfates. By these means a-high percentage of the lead sulfid is converted into lead oxid, and for practical purposes the amount of lead sulfate left in the charge is of no importance. The amount of carbonaceous material added will vary according to the composition of the ore, butwill rarely exceed ten per cent. of the ore charge. The roasted ore after removal from the furnace is mixed with coal or mixture which on carbonization will produce a coke and submitted to'a zinc-distilling temperature in a retort or muffle-furnace in such a way that the flames or gases from the furnace shall not come into direct contact with the ore charge. This operation may conveniently be carried out in an ordinary zinc-distilling furnace. The result of this treatment is the production of metallic zinc and metallic lead. At the tern perature of the furnace zinc is given off in the form of vapor, which is condensed to metal in the usual way. The lead, gold, silver, iron, and silica are left behind in the retort and suspended or hung up in a carbonaceous sponge or skeleton to be subsequently smelted.

In order to prevent the deleterious effect of the lead upon the retorts used, it is necessary to use an amount of coal of a bituminous character in considerable excess of the amount theoretically required to reduce the oxids; but its actual amount will vary with the different ores under treatment. The carbonaceous material cokes and forms a spongy matrix in which the particles of metallic lead, iron silicates, or other fusible substances are retained, so that their harmful action upon the retort is prevented.

I find it greatly advantageous to briquet the charge of roasted ore and carbonaceous material before charging the same into the furnace, with the object of coking the mixtu re into coherent masses. For this purpose bituminous coal or charcoal, anthracite, or similar material, inconjunction with a coking or binding material-such as tar, molasses, or pitch, or similarsuitable materialmay be employed. When briqueting is employed, a less excess of carbonaceous material may be used.

By means of briqueting the reducing agent is more intimately brought into contact with the oxide than can be efiected by the best possible mixture of the dry powders. Further, each briquet becomes an independent distilling center, and the zinc vapor has no great distance to force its way out, as it would in the case of mixed powders in bulk. Briqueting also prevents the reduced lead particles from running together, and in consequence of the metal being held in the form of minute particles-throughout the coke there is no danger of this metal attacking the retort-walls, which otherwise, in the case of direct distillation of the powder, tends to happen with harmful results.

The residue after extracting the zinc by distillation, as hereinbefore described, is smelted by any well-known method for the recovery of the lead and gold and silver and the separation therefrom of iron, silica, and other impurities that may be present.

Should any small amount of zinc be left in the residue, this will. largely be recovered with the subsequently-smelted lead and will serve a useful purpose in desilverizing the latter according to what is known as Parkess method.

If the complex lead-zinc ore to be treated is considered too poor in either constituent for practical smelting purposes, under this invention it may be initially enriched to the required extent by the addition before grinding of galena or zinc-blende.

What I claim as my invention, and desire to secure by Letters Patent, is,

The process of treating sulfid ores containing silver, zinc and lead which consists in roasting the ore to the form of OXldS, mixing the roasted product with carbonaceous material suitable for coking, forming the mixture into briquets, and distilling the briquets under such conditions that they are first coked into coherent masses and finally the zinc reduced and volatilized while the lead is reduced and the lead and silver retained in minute particles throughout the coke.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

HUGH FI'IZALIS KIRKPATRlGK-PIOARD.

Witnesses HAROLD WADE, HARRY DRIDGE.