US1149754A

US1149754A - Mechanical ore-roasting and like furnace.

Info

Publication number: US1149754A
Application number: US66084411A
Authority: US
Inventors: John Harris
Original assignee: Individual
Current assignee: Individual
Priority date: 1911-11-17
Filing date: 1911-11-17
Publication date: 1915-08-10
Anticipated expiration: 1932-08-10

Description

J. HARRIS.

MECHANICAL ORE ROASTING AND LIKE FURNACE.

APPLICATION FILED NOV. 17. 1911.

1,149,754. Patented Aug. 10, 1915.

COLUMBIA Pm. CO" WASHINGTON. II. C.

JOHN HARRIS, or SHEFFIELD, ENGLAND.

"MECHANICAL 'onn nons'rme A ND LIKE FURNACE.

Specification of Letters Patent.

Patented. Au :10, 1915.

Application filed November 17, 1911. SerialNo. 660,844.

To all whom it may concern Be it known that 1, JOHN HARRIS, a subject of the King of England, residing in Shefiield, in the county of York, England, have invented certain new and useful Improvements in or Relating to Mechanical Ore-Roasting and like Furnaces, of which thefollowing is a specification.

This invention relates to mechanical ore roasting and'like furnaces for use in the generation of gases for the production of fluid acid its object being to prevent the creation of dust within the furnace and to obtain'an increased purity and clarity in raw acid produced fromthe furnace gases.

It iswell known that dust arising within the furnace iscarried along with the gases evolved therein -and isthe cause of part of the impurity and of nearly the whole of the discoloration in the raw acid. Various attempts have been made to solve this dust problem but they have not succeeded to any appreciable degree in reducing the discoloration and-increasing the purity of the raw acidbecau'se they have been directed to the symptoms instead ofto the causes of the trouble.

'I have" found that the greaterpart if not the whole 'of the dust causingthe discolorationandconsequent impurity of the acid is.

thatwhich arises from that portion of'the ore or other material being roasted which-is yet in acom-parati ely cold condition and the main feature of the present invention consists in so treating the charges of ore or like material during the initial stagesof the roasting operation that dust pollution of the gases supplied to the acidproducingprocess is eliminated during such initial stages. In thepreferred method of effecting this the material is fed to the furnace intermittently and each batch is wholly removed fromthe delivery area before the next arrives and is then so manipulated that it travels gradually and uniformly along a'predetermi'ned p ath' in such manner that partially heated portions are'not'moved back to mix with colderp0rtions, and the latter do not overtakeand'mixwith parts at a higher temperature, for'l have found that one of the'most fruitful sources of the noxious dust isthe promiscuous mixing of material-at diiferent temperatures, whether the mixing is 'eifected by feeding the material upon that already in the furnace or whether it takes place subsequent to delivery while the material is'still at a temperature substantiallybelow that of its surroundings. The extent of this manipulation will depend upon thenature of the material being roasted, but generally it is advisable to continue it until the material reaches approximately the temperature of its surroundings. Beyond this point any desiredmeans for manipulating the material maybe employed. v Additional devices-tending to reduce the formation of dust may also be employed if desired, such as'the employment of sealed discharges, seals around.

the rabble'shaft and by so arranging the gas apertures in relation to the ore openings that the ore does not drop intheIpath ofthe draft through the furnace.

The-accompa-nving drawi gs are diagrammatic of the preferred method of carrying out this invention, Figure lfrepresenting a sectional elevation-of a-furnace and-Fig. 2 a

sectional plan of the first hearth, o the line i The" furnace shown comprises three superimposed roasting 'ehambersA, A and A? and the 'ore or,-.other material to be' roasted is fed intermittently through the feed opening B to the uppermost chamber A -by' any desired meanssuch as'rabble arms A working upon the roof of the furnace. Each batch of material is then moved gradually anduniformly forward along the desired path'by inclined rakes-C C on the rabble arm D carried by the shaft E adjacent to which the material falls. It' is desirable-for each batch ofmaterial to be spread also completely around; the shaft E, else a portion of the hearth of the chamber will not be utilized. For this purpose the first inclined rake C acting upon eachbatch of material is ofsuch-len'gth and inclination having regard to the quantity 7 of material in each bat'c'h' that the latter is spreadcompletely ing Bby the inclined rake C and that the a next batch Will be fed upon a clear space out of contact with ore or like material at a higher temperature. When the inclined rake C reaches a newely delivered batch the previous batch has been moved if not en tirely beyond the area traversed by this rake at any rate so far from the shaft that the new batch is not mixed therewith. Simi larly each of the inclined rakes C leaves a clear space behind it upon which material is moved by the adjacent rake on the shaft side, and so there is no harmful mixing of material at different temperatures.

The path of the outer edge of each of the inclined rakes (l coincides with or overlaps thatof the adjacent inner edge of the next rake in order to insure that all the ore displaced by one rake comes under the action of the next one and is not left be tween them to mix with that moved by the first rake at the following revolution.

v It willbe understood that, as is the generalpra'ctice in this class of furnace, the floors of the chambers A, A and A are lined with powdered anthracite, coke or the like. The lining will also form a circular wall around the shaft E co-inciding with the path of the outside edge of the outermost rake carried by the arm D except where this path'is overlapped by that of the arm D as shown in Fig. 2. Hence the ore coming under the action of the outermost rake C on the arm D will be limited in its radial movement by this wall which, co-acting with the said outermost rake, will enable the latter to carry the ore around the shaft and to deliver it to the area traversed by the arm D whence it will be moved by the rakes on the arm D The area traversed by the inclined rake C ispreferably raised above the bed of the chamber A in order to decrease the length of fall of material being fed to the furnace and to prevent the possibility of material which has left this inclined rake moving backward to mix with a newly delivered batch. This raised table G may be simply formedwith the powdered anthracite, coke or the like which the floors of the chambers are lined by arranging the lower edge of the inclined rake C at the requisite distance above thefloor of the chamber. When feeding this lining substance through the furnace initially it will of course fill in the space below the rakes.

' The second rabble arm D which acts upon the ore or like material .Will be provided with inclined rakes C, with plow rakes F or the like or with both according to the substance being treated and its temperature when it reaches the area traversed by this arm.

The gases evolved in the furnace are led tothefacid producing process by the flue A other method of manipulating the material during the initial stages of the roasting operation so as to feed it gradually and uniformly forward and to keep portions thereof which are at different temperatures from promiscuous admixture may be employed without departing from this invention, and there may be combined therewith additional devices tending to reduce the formation of dust within the furnace. For example, the discharge of the furnace may be sealed by continuing the casing H of the conveyer J substantially beyond the end of the conveyer, thus causing the material to fill completely this extension of the casing before any portion arrives at the outlet H Seals may also be provided in the feed apertures, B, B and B as indicated by the inclined plates B therein, and around the rabble shafts. Such last mentioned seals may be formed by annular plates K surrounding the shafts E and covering the openings in the roasting chamber floors through which the shaft passes. The plates are preferably loose so as to allow of relative movement between the shafts and floors and to prevent damage by any solid body which may accidentally be situated in the path of the rabble arms. In combination with each of these annular plates K an advanced plow, indicated at L, is carried by the rabble arm to move any material being roasted away. from the shaft openings in the arched floors and to direct it under the action of the adjacent rabble rakes.

A. further arrangement preventing the formation of dust is to dispose the gas apertures Min relation to the feed openings B, B and B so that the oredoes not drop in the path of the draft through the furnace. This may be effected by arranging the gas apertures M at the corners and the feed openings in the center line of the furnace as shown clearly in Fig. 2. Both may, however, be centrally disposed as indicated in the arched floor of the chamber A and in this case the feed opening is situated on that side only of the gas aperture which is opposite to the direction from which the draft through the furnace comes.

What I claim and desire to secure by Letters Patent is 1. The herein described method of treating ore in a roasting furnace comprising intermittently feeding charges of ore to the furnace and moving the different batches over the hearth surface therein in such manner that the successive charges are maintained separate throughout the process, whereby mixing of charges having different temperaturesis prevented, for the purpose described. I

2. The herein described method of treating ore in a roasting furnace comprising intermittentlyfeeding charges of ore'to the furnace and moving the different batches across each of a plurality of hearths and from one hearth to another in such manner that each charge is removed from the delivery area of a hearth prior to the delivery thereon of a following charge, whereby a plurality of successive charges are maintained separate on said initial hearth and throughout the roasting process until they have reached substantially the same temperature, for the purpose described.

3. The herein described method of preventing the formation of dust in the operation of roasting ore in a furnace wherein the ore is moved over a hearth by rabbles on a rotating shaft, compnsing intermit- Gopies of this patent may be obtained for five cents each, by addressing the tently feeding ore onto the hearth adjacent the shaft, the amount of each charge being limited to that which can be displaced at a revolution of the shaft, whereby the delivery area of the hearth will be cleared of eachcharge before another charge is deposited thereon, and maintaining the successive charges separate while they differ materially in temperature.

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

JOHN HARRIS.

Witnesses:

ARTHUR H. GREENWOOD, LUTHER J. PARK.

Commissioner of Patents.

Washington, D. 0