The arrangement of equipment directly ahead of the reactors is as follows: Flotation concentrates are pumped first to a small thickener then to a small rotary vacuum filter, with filter cake, at 12 per cent moisture or less, going to the reactor and with thickener overflow and filtrate going either to waste or back to the flotation circuit. Every run was done in duplicate. Many sulfide minerals contain other components such as arsenic that are released into the environment. This process released large amounts of acidic, metallic, and other toxic compounds. An outstanding advantage afforded by the invention is that operations may be carried out in simply constructed and economically maintained apparatus. but is never less than 12 hr. The method for roasting metal sulfide smalls containing coarse sulfide ore and initial sulfide fines which comprises introducing the smalls into an oxygen-containing combustion zone heated to temperatures not less than about 1300° F. whereby the smalls are suddenly subjected to temperatures of the combustion zone and the coarse ore is converted to a relatively porous frangible condition and partially roasted, maintaining such temperatures by at least partial combustion of some of said smalls, subjecting the coarse ore while in said zone to attrition sufficient to reduce the same to fines, then introducing such resulting fines together with said initial fines into a second combustion zone, forming therein a suspension of fines in oxidizing gas, roasting the fines while in suspension in the oxidizing gas to produce sulfur dioxide, and recovering sulfur dioxide. Utilizing the principle of such discovery, I have developed a method which may be employed to marked commercial advantage for roasting ores such as pyrites smalls. drop in the bottom of the roaster, which completely stops back mixing of the charge between the cooling hearth and the roaster proper. Studies by Queens University, Ontario, Canada, connected with special methods of roasting arsenical ores resulted in the finding that: After heating arsenical ores or concentrates mixed with soda ash equal to 5 to 10 per cent of their weight in the absence of air for a period of 20 to 60 min. To avoid loss of gold, the amount of salt added must be held at such a figure that this volatilization does not occur. Figure 49 shows a generalized cross-sectional view of the FluoSolids reactor which has recently been developed and is now being applied to the roasting of sulphide ores, to the calcination of various materials, and in general to problems involving reactions between solids and gases at elevated temperature. Residual values of about 1.8 dwt. The roasting of ores containing arsenopyrite presents greater difficulties than straight pyritic ores mainly because of the tendency toward the formation of insoluble arsenites and arsenates, which have a detrimental effect on gold recovery. The fresh feed entering the furnace falls into this bed of dry, dusty material and picks up a coating of dust. NaCl to the Lake Shore concentrate does not cause any measurable volatilization of gold in the plant roasters. During roasting, the sulfide is converted to an oxide, and sulfur is released as sulfur dioxide, a gas. This arrangement is made by providing a 10½-in. concentrate could be extracted by quenching in water alone without the use of any cyanide at all. The bottom of the combustion chamber is formed by a cone-shaped hearth or hopper 40, of substantial vertical length, terminating in a cinder discharge opening 42 which may if desired be provided with a gas lock mechanism through which cinder may be discharged without permitting gas to escape from the combustion chamber. Lying above the hearth are rabble arms 19 having downwardly projecting plows 20 pitched to work sulfides gradually toward the circumference of the drying hearth. Samples for each run weighed 150 grams. The trouble previously experienced owing to build-up on the rim of the agitators disappeared. The current tonnage of concentrates handled in the reactor is 8 tons per day assaying about 6 oz. In the second roaster, the number was decreased to six pairs. Once batch agitation was instituted, most of the difficulty of a mechanical nature disappeared from the calcine cyanidation. Leave your phone number if you would like us to call you. In this chemical change the iron mineral is rendered more or less porous, thereby permitting the dissolution of the contained gold by subsequent cyanidation. These aerators are made of 8-in. The result of operation of the preliminary grinding-roasting phase of the process is such as to quickly and cheaply reduce all of the coarse ore particles to suspension roasting particle size and to effect some roasting of all of the ore with consequent production of some sulfur dioxide. The spongy porous nature of the calcine adds to the difficulty of washing the cake. In general, serious gold loss by volatilization is not experienced in roasting gold ores or concentrates provided that the chloride content of the feed is below a certain critical figure (at Lake Shore this was 30 lb. 6. patent previously mentioned. Silver ores containing the values as polybasite, stephanite, pyrargyrite (the antimony sulphide), and proustite (arsenic sulphide) usually require roasting. Because the Cochenour Willans ore is self-roasting, temperatures are controlled at about 1100°F. Argentite (the silver sulphide) and cerargyrite (the chloride) can frequently be cyanided without roasting. motor drives the complete mechanism of each roaster. The removal of this build-up necessitated shutting down the agitator and chipping off the accretions, which at times were well over a foot thick. The roast changes the pyrite grains into porous friable hematite which allows the cyanide solution to penetrate to and dissolve most of the gold values. There are two outlets in the dome top of the reactor, one, 14 in. gold per ton. Often before roasting, the ore has already been partially purified, e.g. However, since the rate of gas movement upwardly through chamber 14 is appreciably less, on account df the relatively large cross-section of chamber 14, than the velocity of the gas stream passing thru chamber 58, the fines particles soon lose their initial momentum and for the most part drop more or less vertically through chamber 14, dotted line 105 on the drawing indicating the general course of a fines particle through chamber 14. at the fifth port and rises slowly to a maximum of 1150° at the eighteenth port. This invention is directed to methods for roasting sulfide ores to desulfurize the same and to produce sulfur dioxide for use in the manufacture of sulfuric acid, or for any other purposes desired. Korundal sphere is seated. In accordance with the present process, on account of the exceedingly frangible condition to which the coarse ore is rapidly converted, whatever grinding is necessary may be accomplished with much less ex7p penditure of power than would be the case if the coarse ore constituents were pulverized in usual grinding operations. A subr.antial portion of an ore of this type is sufficiently finely divided for suspension roasting if separated from the coarser material, although a large portion of the smalls, in many cases the ::; major portion, comprises ore too coarse for suspension roasting by present methods. The high sulphate content of the calcine pulp gave rise to another problem. by a lining of 9-in. The continuous process was abandoned in favor of batch agitation. It was later found that 94 per cent of the gold in a 1.92-oz. For information on the cyanidation of the calcine see the general mill description in Chap. The material passes down from one compartment to the next through “overflow” standpipes, and the countercurrent flow of gases and solids makes it possible to effect considerable heat economy where this is desirable. The pulp from the calcine mill is pumped to one of the pair of tanks until they are filled. A number of examples of calcine treatment will be found in Chap. The method for roasting metal sulfide smalls 60 containing coarse sulfide ore and initial sulfide fines which comprises maintaining an oxygencontaining combustion zone at temperatures not less than about 1300° F., introducing the smalls into said zone whereby the smalls are suddenly 65 subjected to temperatures of the combustion zone and the coarse ore is converted to a relatively porous frangible condition and partially roasted, subjecting the coarse ore while in said zone to attrition sufficient to reduce the same to fines, then introducing such resulting fines together with said initial fines into a second combustion zone, forming therein a suspension of fines in oxidizing gas, roasting the fines while in suspension in the oxidizing gas to produce sulfur dioxide, and recovdring sulfur dioxide. One end of furnace 55 is provided with a fixed head 66, supported by framework not shown and arranged in relatively gas-tight relationship with the end of the shell 56.