US1905604A

US1905604A - Process of roasting ores

Info

Publication number: US1905604A
Application number: US546892A
Authority: US
Inventors: Queneau Augustin Leon Jean
Original assignee: Individual
Current assignee: Individual
Priority date: 1931-06-25
Filing date: 1931-06-25
Publication date: 1933-04-25
Anticipated expiration: 1950-04-25

Description

A ril 25, 1933. I -A. J. QUENEAU 1,905Q604 PROCESS OF ROASTI'NG ORES Filed June 25', 1951 .4: U a GI 7 3 l I ALL 51 w HI INVENTOR av g a r ATTORNEYS Patnted' 1 r.25 1 33 f.

UNITE-o STATES- PATENT Ol fFlCEf. 7

mav ns LEO Juan QUENEAU, ornnw YORK, Y

rnocriss or 'noasrme onus Application filed June 25,

This invention relates to "metallurgy and more particularly to methods of treatlng ores and metal bearing materialsto facilitatethe recovery of the metal bearing constituents thereafter recovered from the roasted re'sidues in any convenient'manner.

Inthe oxidizing of zinc sulphide ore, it is customary to pass the ore through a roaster in order to liberate the sulfur and to bring about. a transformation of the zinc sulphide to zinc oxide so that metallic zinc can be re-v covered the'refromby lmown methods of pyro-metallurgy. V i

- In the oxidizing of zinc sulphide ore, it has been found that anexcessive heat is developedat certain places within the roastingiurn'aces which causes a detrimental fusing ofthe ore and brings about an agglomeration of the charge. This solidification or agglomeration interferes very materially with the operation of the furnace 'and requir es frequent shutdownsfor the purpose'of breaking up the charge. Air cooling at such zones has been resorted to. This is objectionable 'as it increases the volume of outgoing gases and also increases the dust carryingcapacity thereof."

It is one of the objects of the present invention. to eliminate this detrimental fusing of the zinc sulfide ores during the oxidizing of the -same.-

Another object of the present invention is Q to improve the method ofoxidizing zinc sul- Another object of the. present invention is to provide an improved type of ore roasting apparatus.

will become apparent as the invention is'more fully disclosed. In accordance with the objects of the present invention I have found thatthisdetri mental heating of the ore usuallypcc'urs'with Theefiluent .ly large quantity of dust particles whichare reintroducing of the dust 1931; "Serial in. 546,892.

in the furnace between the fifth and seventh heartlis (counting from the top) in astand- -ard type of' 16 hearth roasting furnace customarily used.

' I have 'also found that thisv detrimental 55 heating may be overcome by: introducing .within the furnace and upon the hearth or I hearths wherein this 1 detrimental fusing occurs, a proportion of inert material, ref-' erably of relatively high heat absor ing value, thereby'ofisetting the tendency of the ore'to liberate the excessive heat energy at this point.

furnace gases carry a relative-- comprised of a relatively high proportion of zinc sulfate. To-convert zinc sulfate into zinc oxide and. sulfur oxide products arelatively large quantity of heat must be applied thereto. I propose therefore to recover the dust product of the-efiluent gases of the furnace and to return-the same to the furnace at the zone where excessive heating usually takes place thereby utilizing the endothermic reaction of the thermal decomposition of-the zinc sulphate contentof the dust product to bring about a cooling of the oreunder. treat- 7 ment at the critical zone; Before further disclosing the nature'and scope of the present I invention, reference shouldbe made to the following drawing wherein; The figure is a vertical longitudinal section through a roasting furnace suitable for I carrying out the method of the invention,

' the view also diagrammatically showing cer- 5 tain related apparatus 'for the collecting and product into the hot zone of the furnace. v Referring in detail to the drawing, 10'represents a roasting furnace of known construction which is usually provided with a J plurality of superimposedshelf-like hearths 12' having central openings 14:. Stirring arms 16 carried by a centrally disposed ro- These and other objects and advantages tatable shaft 18 serve to feed the pulverized ore along-the hearths. Fuel such as natural gas, clty gas, oil. or the like may be .,introduced within the" furnace through a suitable burner 22.

the excessive heating takes place in the zone between the fifth and seventh hearth.

The heated and oxidizing gases arising in the furnace from burner 22 carry off a dust product containing a substantial proportion of zinc sulphate (ZnSO These gases and the entrained dust are taken off at the top of the roasting furnace through a pipe 26 and led to a suitable dust separator 28. The dust is trapped in the separator and flows through a pipe 30 to a bin 31 and thence to a screw conveyor 32 which introduces the dust containing the zinc sulphate onto the hearth located at the predetermined critical zone.-

A pipe 34 connected to the dust collector carries oif'the sulphur dioxide to a suitable apparatus (not shown) for the recovery of sulphuric acid. Y

The zinc sulfate content of the dust thus introduced is thermally decomp sed by the heat energy of the furnace to form zinc oxide and sulfur oxides compounds. This reaction is endothermic innature and requires a relatively high temperature approximating 770 C. In addition the dust particles because they are relatively cold have a distinct cooling effect on the temperature of the charge independent to the endothermic ther; mal decomposition reaction.

From the foregoing it will be readily apparent that according to my novel method the cooling of the charge ofore und er treatment is brought about solely by 1ntroduct1on of the dust product recovered during normal treatment and withouttlie introduction of any cooling air. Thus the cooling effect is secured without increasing the volume of outgoing gases and consequently without multiplying the dust carrymg capacity of such gases. The advantages which accrue as a result of the improved method will be readily appreciated by those skilled in the art.

While I have described with great particularity certain specific steps in the preferred method it is not to be construed that I am limited thereto and the detailed description is to be interpreted in 'an illustrative rather than a limiting sense since various modifications may be made by those skilled in the art without departure from the scope of the invention as defined in the appended claims.

What is claimed:

1. In the roasting of ores, the method of controlling the temperature of the roast which comprises adding at an intermediate pointin'the roasting process where the temperature is excessive increments of thermally decomposable material of relatively high heat absorbing capacity.

2. In the roasting of ores, the methodofcontrolling the temperature of the roast which comprises adding at an intermediate point in the roasting process where the temperature is excessive during the roasting operation increments of thermally; decomposable 'material of relatively high heat absorbing capac- 1 3.- In the roasting of zinc sulfide ores, the method of controlling the temperature of the roasting operation which comprises adding at an intermediate point in the roasting process where the temperature is excessive incre- V ments of thermally decomposable material of relatively high heat absorbing capacity.

. 4. In the roasting of zinc sulfide ores, the method of controlling the temperature of the roasting operation which comprises adding at an intermediate point in the roasting process Where the temperature is excessive increments of zinc sulfate.

5. In the roasting of zinc sulfide ores, the method of controlling the temperature of the roasting operation which comprises adding at an intermediate point in the roasting process where the temperature is excessive increments of material comprised in part of zinc sulfate.

6. In the roasting of zinc sulfide ores the method of controlling the temperature of the roasting operation which comprises adding to the ore at a predetermined point in the furnace where the temperature during the roasting becomes excessive, a proportion of a material comprised at least in part of thermally decomposable material of relatively high heat absorbing capacity. 4 v

7. In the roasting of zinc sulfide ores the method of controlling the temperature of the roasting operation/which comprises adding to the ore at a predetermined point in the furnace where the temperature during the roasting becomes excessive, a proportion of a material comprised at least in part of zinc sulfate.

8. In the roasting of zinc sulphide ore the method which includes the step of utilizing zinc sulphate (ZnSO to exert a cooling action on the ore at a predetermined point in the roasting furnace where-the roasting temperatures become excessive.

9. A method of roasting zinc sulphide ore. which comprises feeding the ore in a finely divided state through an atmosphere of hot oxidizing gases, collecting the resulting dust product containing zinc sulphate (ZnSO.) and returning said duct product to the ore under treatment at a predetermined zone where the roasting temperatures become excessive so as to utilize its endothermic reacmethod which comprises feeding the finely divided ore successively over a plurality of hearths of a roasting furnace, subjecting the ore to the heat of'reaction of an oxidizing gas in the roasting furnace,carrying off the resulting gases and a fine dust product comprised at least in part of zinc sulphate, zinc oxide and gangue, collecting such dust product and reintroducing it at a predetermined zone of the furnace where the roasting temperature becomes excessive to effect a cooling of the ore under treatment in said zone.

11. In the roasting of zinc sulphide ore, the method which comprises feeding finely divided ore gradually over the heart-hs of a roast ing furnace, subjecting the ore to an atmosphere of oxidizing gases in said furnace, collecting a dust product carried off with the outgoing gases which product includes a. substantial percentage of zinc sulphate, and mixing such dust product with the ore under treatment at a predetermined zone within the furnace where the roasting temperature become excessive so as to utilize the endothermic reaction of the zinc sulphate content in the dust product to effect a reduction of temperature of the ore under treatment in said zone.

In witness whereof, I have hereunto signed my name.

AUGUSTIN LEON JEAN QUENEAU.