US962493A - Method of making sulfuric acid from smelter-gases. - Google Patents

Description

Patented June 28, 1910.

' fmehiorax J. P. GHANNINGK: P. J. EALDING.

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APPLICATION FILED MAY 14, 1908. RENEWED JAN. 4, 1910.

Wneasea I T STATS JOHN ra'nm CHANNING AND FREDERIC JOHN FALDING, OF NEW YORK, N. Y.; SAID FALDING- ASSIGNOR T0 SAID CHANNING.

METHOD OF MAKING STJ'ICEU'RIC ACID FROM SMELTER-GASES.

Specification of Letters Eatent.

Patented June 28, 1910.

Application filed May 14, 1908, Serial No. 432,781. Renewed January 4, 1910. Serial No. 536,404.

To all whom it may concern:

Be it known that we, JOHN PARKE CHAN- NING and FREDERIC J. FALDING, citizens of furic Acid from Smelter-Gases, fully de-' scribed and represented in 'the following specification and the. accompanying drawings, forming a part of the same. This invention relates to an improved method of utilizin the furnace gases given;

off from smelting idirnaces during the operation of smelting sulfid ores pyritically, and it particularly relates to an improved method of controlling the furnace gases so as to obtain gases having a certain composition, and treating such gases to produce sulfuric acid therefrom.

In smelting sulfid copper ores py'ritically, as 'now carried out, the ore (not pre viously roasted) is treated in a blast furnace with an addition of a certain amount of carbonaceous material, the oxidation of the charge being accomglished by blowing certain quantities of air therethrough. This action results in an oxidation of a portion of the iron and sulfur content in the ore, which provides nearly all of the heat necessary for the process. The portion of the iron and sulfurwliich is not oxidized, com bines with the copper and forms a substance known as matte 'which is drawn off from the furnace and-further treated to obtain the copper therefrom. The sulfur dioxid (S0,) passes through the furnaces in theform 0 a as, together with certain other gaseous su stances. While, theor. tically,

treated to produce said gases profit-ably by our invention.

We have discovered that to successfully from which the sulfuric acid is obtained.

use these furnace gases in the manufacture of sulfuric acid, the relative proportion be tween the amount of sulfur in the charge and the amount of coke added thereto must be such, that sufiicient free oxygen to convert the sulfur dioxid into the sulfur trioxid should be present in the gases. If too much coke is used, the gases are not suitable for manufacturing sulfuric acid, because so much of the oxygen in the air blown into the furnace is taken up in oxidizing the excess of coke into carbon dioxid that there is not enough oxygen left in the gases to convert the sulfur dioxid into sulfur trioxid,

Such oxygen cannot, under such conditions of excess of coke, be replaced by supplying more air to the gases, for the reason that in the air supplied so much nitrogen is present that the resulting gases are diluted to such an extent lasdzo be unfit for use, being too weak in sulfur dioxid.

One part of our invention consists in keeping the carbonaceous material, or coke, used in the smelting furnaces, in a certain proportion to the sulfur content in the I charge to be smelted, the proportionof said carbonaceous material to be maintained as low as possible, and yet not interfere with the smelting operation, in order to .obtain gases containing sufficient oxygen relatively to the sulfur dioxid.

In practice, we have found that about one per cent. of carbon to about four percent.

of available sulfur in the charge is a proportion which produces gases having sufiicient oxygen therein to convert the sulfur dioxid into sulfur trioxi'd during the process of converting the sulfur dioxid into sulfuric acid. To give a concrete example, in an ore containing twenty-five per cent. of sulfur, about twenty per cent. of which will be oxidized or available, the balance of which will combine with the iron or copper to form the matte, we find that five per centof coke is 100 sufliclent to allow for the proper operation of a smelting furnace, and at the same time to obtain gases sufiiciently rich in oxygen. It is found in practice, furthermore, that the amount of free oxygen in the gases should 105 be, to obtain the best results,considerably more than the amount theoretically required to convert the sulfur dioxid into sulfur trioxid. For example, assuming that the gases contain six per cent. of sulfur dioxid, such 110 ing doors in any considerable quantity, the

, gases are madeso weak or dilute as to be unsuitable for conversion into sulfuric acid, and such air should be excluded. If, however, the gases are too rich in sulfur dioxid, they may be diluted.

.. In addition to having sufficient oxygen in the gases to convert the sulfur dioxid into sulfur trioxid, the gases containing the sulfur dioxid supplied to the acid making apparatus must have a certain content or per centage of such sulfur dioxid. This content should be approximately from five to eight per cent. sulfur dioxidof the total gases supplied to the acid making apparatus.

The. gases shouldpref'erably be at least as rich as approximately five per cent. in sulfur dioxid, for if poorer than such percentage the reactions taking place in such apparatus are slow and not sufficiently intense,

and the apparatus consequently has to be so extensive that its cost in maintenance precludes the ossibility of making sulfuric acid profitably. The gases should 'not be richer in sulfur dioxid'than approximately ei ht per cent, as a higher percentage of su fur-dioxid would preclude the possibility of there being suflicient free oxygen for the 7 process.

percentage of sulfur dioxid in the gases,

proportions, and which Again, whatever the particular such percentagemust be substantially constant, owing to the nature of the reactions which take place during the conversion of the" sulfur dioxid into sulfuric acid, and owing to the physical conditions under which the reactions take place. The gases thus obtained from a furnace or furnaces working perfectly, and in whichthe carbon, sulfur and air are present in just the right ases contain the ercenta es of sulfur dioxid and oxygen inicated a ove, can be used for making sulfuric acid without further treatment by the well-known chamber or contact processes.

Such ideal'conditions, however, would seldom, in actual practice, be present, and ifso, could not be ractically maintained for any considerable ength of time, as the gases from "the furnaces vary constantly. Where a number of furnaces are used, gases having varying contents of sulfur dioxidand oxygen are given oil", the content'of each furnace being different from that of the others, and it would be extremely difficult to keep these contents sufiiciently constant foruse in making sulfuric acid.

before indicated, in a suitable receiving chamber or reservoir, a mixture of gases is obtained which contains a readily ascertalnable content of sulfur dioxid and oxygen,-

such content being the average of the vary ing contents given offby the different furnaces. lVhere, therefore, a plurality of furnaces are operating, and the gases from the different furnaces vary in their content of sulfur dioxid and oxygen, we collect such gases from the furnaces in a chamber or reservoir and allow them to commingle or mix, and the resulting gases have a content of sulfur dioxid and oxygen which is the average of the varying contents given ofi by the different furnaces, such content being thus equalized. This final content is readily as certainable, and can be readily obtained by suitable adjustment and control of smelting.

and collecting conditions to give the right percentage of sulfur dioxid and oxygen by admitting gases richer in sulfur dioxid or oxygen, or both, to the reservoir from a furnace producing'such gases, iftheaverage content is too weak in either. If such content has approximately the amount of sulfur dioxid and oxygen which should be present,

as before indicated, the gases are then passed into a sulfuric acid making apparatus, elther of the chamber process type, or the contact process type.

If the content of the gases from any furnace is too rich in sulfur dioxld, it may be diluted by admitting air to such gases before entering the reservoir,' or lf-th average content of the gases in; the reservoir is too rich in sulfur dioxid, it jfmay' be diluted by admitting air to such gases, either in the reservoir or after leaving the same, before entering the Glover tower ,of the apparatus of the chamber process type, or before entering the apparatus of the contact process type; or if the gases would be cooled too much for the concentration function of the Glover towers in the apparatus of the chamber process type, such air were fldlnlttd b6f01 the gases enter the same, then the air may be admitted to them after" theypass such Glover towers. The gases can in thisiyvay be maintained'with a practically constant percentage ofsulfur dioxid and oxygen, suitable .for conversion into sulfuric acid.

This treatment'may be carried out in various apparatus, and we will now descr be it in connection with one apparatus for carrying it out. The apparatus which will now be described is, we have found, a, convenient one for such treatment-of furnace gases, but

20 parts in which the charge to be smeltedis ceases it will that our invention is ppar u In} th 'iaccoinpanying drawings :-Figure 1 shows adiagrammatic plan view of an apparatus fortreating furnace gases, and also a filter, and one Glover tower of the sulfuric acid making apparatus of the chamber process type and Fig. 2 shows diagrammatically and partially in section an elevation of a portionof the same apparatus, or plant, shown in Fig. 1'.

Referring now'to' said drawings, the apparatus shown comprises'a plurality of smelting furnaces which are shown diagrammatically in Fig. 1, and'aremarked, respectively,-1, 2, 3 and 4. The number of such furnacesmay be widely varied. Thefurnaces are of any usual or 'desired construction and, as shown, comprise (see Fig. 2)

dumped; charging doors 6, which should be approximately air tight, located near the tops, also approximately air tight, and means such as 7, for blowing air in through the charge being provided. A stack 8, of

suitable construction, for carrying off gases and giving the required draft, is also provided, as is usual, in suitable relation to the furnaces. As before indicated, by' mixing or commingling the gases given off from a number of different smelting furnaces, more uniform gases are obtained, a d to so mix or commingle the gases there s provided a chamber or reservoir, common to all the fur-.

naces, in which the gases from the different furnaces are collected, and a certain flue construction for controlling the gases, and these constructions will now be described.

As shown, rising from the top of each of the furnaces is a short vertical'flue or pipe 9. Each flue or pipe 9 communicates with a horizontal flue 10, one of which is provided at eachfurnace. niunicate with a flue or passage 11, common to all of the flues 10. This fine 11 is a bypass flue, the function of which will be hereinafter referred to. The horizontal flues 10' from all the furnacesmay be collecte 'by' meansof the fines 9, 10 and 12, as described, and commingle or niix therein. This chamber or reservoir 13 is in communication with a flue or passage 1a which communicates with the flue 30 leading to the stack 8, the flue 3O bein The flue 14 a so communicates with the fiue or pipe 17 connected with the acid making apparatus and controlled by a damper 29.

The chamber or reservoir 13 is preferably divided by a longitudinal partition 31 hav ing two openings 33, and by a transverse partition 32, to cause the gases to more thor- These flues 10 com controlled by a damper 19.

to the other parts of the apparatus of the contact process type. As the apparatus of both types, and the rocesses and reactions which the gases un ergo therein, are well known, it will not be necessary to describe them. The flues 10, or anyone of them, are connected to or disconnected from the bypass flue 11 by dampers 15,-these' dampers being located in the-fines 10 between -the short vertical pipes 9 -rising from the tops of the furnaces and the by-pass flue 11. In the dues 10 are provided dampers 16, .by means of which each of the flues 10 maybe disconnected from, or connected with, said reservoir or chamber 13.

As before stated, all the fines 10 leading from the furnaces are arranged to be in communication with the flue -or by-pass 11. This by-pass fine 11 is closed at one end, and at the other end communicates with the flue 30 leading to the stack 8, so that if desired the gases from all or any one of the furnaces may be passed therefrom without entering thereservoir orchamber 13. "With this arrangement of a mixing chamber common to all of the furnaces, andthe system of dues thus described, the gases produced from the furnaces may be .led lnto this chamber and mixed and commingled, and the varying contents of sulfur dioxid obtained from the different furnaces equalized, the resultant gases, having a content of sulfur dioxid and oxygen which is the average of the varying-contents of the sulfur dioxid 1 and oxygen from the different furnaces, If,

for any reason, one'or more furnaces is not in 'operatlon, or if thegases produced from any one of the furnaces is too. poor in sulfur dioxid or in oxygen, or otherwise unsuitable to be run into the mixing chamber, the gases from such furnace may be directed away therefrom by closing the damper 16, and such gases permitted to enter the -by-pass fine by opening the damper 15', the gases from the other furnaces passlng into the indicated in the drawing; or to the pun ing and cooling apparatus and then introduced at any part of the a paratus be-. tween the dampers 15 and the G over towers of the apparatus of the chamber rocess type, or the purifying apparatus of t e contact process type: Or, it may be introduced I afterthe gases leave the Glover towers in up tothe damper 29, is controlled, an thethe apparatus of the chamber rocess type, or it may be introduced at t e charging doors 6 of the furnace, or by increasin the amount of blast. We have indicated oors 20 in the flues 9, 10 and 12, and a door 21 in the flue leading to the Glover tower, and a door 23 in. the flue leading from the Glover tower for controlling the admission of such air for reducing the mixture to the desired percentage of sulfur dioxid. By these means the ,control of the sulfur dioxid and free oxygen in the gases is permitted,'and a certain relative percentage of each canbe obtained and kept approximately constant.

By-raising and lowering the damper 19 in the flue 30, the draft to the stack 8, and the pressure and consequent tension of the ases excess of gases, beyond whatis required for the acid making apparatus, is earned to the stackv 8. The-gases required for the acid" makin apparatus are drawn forward throng the flue 17 by reason of the partial vacuumin the acid making apparatus causedby the cooling and condensation of the gases therein, or by auxiliary fans, as-

pirators, or other apparatus, or both, as is well known, which partial vacuum isinexcess of thegpartial vacuum existing' in the I 'chamber'13 caused by the connection of such chamber and the'fiue 14 with the flue 30. By

raising and lowering the damper 29 in the flue 17'-the tension of the gases in the filter,-

if it is used, and in the acid making apparatus, isalso controlled. The mixing reservoir or chamber 13 also, serves as a dust chamber, and is pref erably formed as shown in Fig- 1, with a sloping wall 34:, so as to catchflue-dust and other matter which may "pass through the apparatus with the gases,

the door 25 being provided to permit the :removal of such dust or other matter.

As the heat of the'furnace gases is employed in concentratin the acid made in the Glover towers of t e apparatus of the -chamber process type, the ,plpes' and flues leading from the furnaces to the chamber l3 and the pipe leadin from such chamber to such Glover'tower .s ould be made as short.

'as possible and covered by some heat nonconducting material, and the chamber 13 itself should be-likewise protected as much as possible to prevent the radiation'of heat in order that the gases may reach the Glover towers as hot as possible.

What we claim is 1 1.- The method of controllin and utilizing the furnace gases given 0 'in' smelting furnaces during the operation ofsmeltlng sulfid ores pyritically, which consists in keeping the. ercentage of the carbonaceous material in thesmelting of such ore low proportionately to the percentage of sulfur in the ore, so as to obtainggases having certain relative contents of sulfur. dioxid and oxygen, said oxygen being in excess, and

treating the same to produce sulfuric acid.

2. In theart of producing sulfuric acid, the method of controlling-and utilizing the furnace gases given off in smelting furnaces during the operation of smelting sulfid ores pyritically, which consists in keeping the percentage of the'carbonaceous material in the proportion of about one per cent. of such material to about four per cent. of sulfur in the ore, so as to obtain ases having certain 4 lecting such gases froma'plurality of such furnaces, in a chamber where they commingle or mix together, and treating the same to produce sulfuric acid.

4. Themethod of controllin and utilizing thefurnace gases given 0 in smelting furnaces during, the operation of smelting sulfid ores pyriticallyjflwhich consists in maintalnln a certaln pro ortion between the sulfur in the ore and t e. carbonaceous material used in thesmelti-ngof such ore, so as to, obtain ases haying certain relative contents of sulfur dioxid and oxygen, collecting such gases from a" plurality of such furnaces, mixing or commingling them so that the content of sulfur dioxidis from about 5% to 8% of the mixture, maintaining such percentage of sulfur dioxid constant, and treating the same toproduce sul- I furic acid.

- 5. In the art. of producing sulfuricacid, the method of treating furnace gases prodiiced in smelting furnaces'during the operation of smelting sulfid ores pyriticall'y,

which consists in collecting such gases'in controlled pro ortions from a plurality of such furnaces m a chamber wherethey may commingle or mix together, and treating the same to produce sulfuric acid.

6. In .the art of producing sulfuric acid, the method of treating furnace gases produced in smelting furnaces during the operation of smelting sulfid ores pyritically, which consists in collecting such gases from a plurality of such furnaces in. a chamberv mixing controlled conditions until a certain content of sulfur dioxid and oxygen is resent, and

treating the same to produce sul uric acid.

7. In the art of producing sulfuric acid,

the method of treating furnace gases proor commingling said gases undel lHO operation of smelting duced in smelting furnaces during the operation of.smelt1ng sulfid ores"plyriticthe method of treating furnace gases pro-' furnaces during the sulfid ores pyritically, which consists in collecting such gases from a plurality of furnaces in a chamber, mixing or' commingling said gases under controlled conditions until a certain content of sulfur dioxid and oxygen is present in the mixture, adding air after such gases have passed theGlover tower :of the acid making apparatus of the chamber process type, if the content of sulfur dioxid is too rich, and treating the same to produce sulfuric acid.

9. In the art of producing sulfuric acid, the method of treatin furnace gases pro: duced in smeltin rnaces during the operation of smelting sulfid ores pyritically, which consists in collecting such gases duced in smeltin -;duced in smeltin operation of smelting sulfid ores pyritlc- ,froma plurality of smelting furnaces in a chamber, mixin or commingling said gases under controlle conditions so that the content of sulfur dioxid is from 5% to 8% of the mixture and that the oxygen is from 7% to 9%, maintaining such percentage of sulfur dioxid constant, and treating the same to produce sulfuric acid.

10. In the art of producing sulfuric acid, themethod of treating furnace gases profurnaces during the ally, which consists in collecting such gases from a plurality of such furnaces in a chamber Where they may commingle or mix together, and from which they are delivered to they Glover towers of the acid making apparatus of the chamber process type, and maintaining their heat from the time they leave the furnaces until they enter such Glover towers, substantially as described.

In testimonywhereof, we .have hereunto set our hands in the presence of two subscribing witnesses.

JOHN PARKE CHANNING. FREDERIC JOHN FALDING.

Witnesses:

M. B. PHILIPP, T. F. KEHOE.

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