US1835460A - Preparing coked agglomerates - Google Patents

Description

Patented Dec. 8', 1931 UNITED STATES PATENT OFFIE' EARL BUNCE AND THOMAS C. ROUTSON, OEPALMERTON, PENNSYLVANIA, ASSIGNOBS TO THE NEW JERSEY ZINC COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY PREPARING COKED AGGLOMERATES No Drawing.

ates of mixed zinciferous material and carbonaceous material.

The invention aims to provide certain improvements in the preparation of such coked agglomerates.

It has heretofore been found that coked 10 agglomerates of mixed zinciferous and car their place of exit.

These agglomerates are prepared by first I crushing the ore and coal separately, then kneading them together, in a Chilean mill or edge-runner to form a mixture that is sui able for agglomerating. The Chilean mill or edge-runner is frequently referred to as a chaser, its operation as chasing, and the treated material as having been chased.

A binder, if necessary, such as sulfite liquor,

may be added in the last stage of the treatment in the edge-runner. The mixture thus prepared in the edge-runner is then agglomerated and coked, at temperatures insufficient to cause any substantial loss of zinc.

We have found that certain details of the preparation of the mixture of coal and zinc ore or the like before agglomerating influence to a marked extent the ultimate properties of the coked agglomerates, and the essential nature of the present invention relates to a control-of the preparation of thezinc ore and the coal before agglomerating, in such a manner as to secure the production of agglomerates that will not split up ,when coked Such agglomerates must Application filed August 23, 1928. Serial No. 301,709.

and thatwill not disintegrate when smelted in a vertical retort for the distillation of zinc.

The appropriate control of the preparation of the charge for agglomeration involves a proper adjustment of at least the following three factors: (1) nature of the coal, with particular reference to its coking characteristics; (2) particle size of (a) the zinc ore and (7)) the coal, before they are kneaded together in the edge-runner; (3) particle size of the mixture of zinc ore and coal, after treatment in the edge-runner, in the final stage of its preparationfor agglomeration. These three factors may be appropriately controlled in combination, to secure a firm agglomerate consisting of a coke structure intimately bonded with and enveloping the particles of zinc ore, so as to prevent both splitting up of the agglomerates during C(lll" ing and disintegration during the subsequent distillation. v 7 7 We have found that the carbonaceous material used to prepare the agglomerates should be composed in part of a so-called free-flowing coal, i. e., a coal that during coking softens to a great extent, wetting the individual particles of ore, so that when the coke hardens substantially each ore particle is enveloped in and in intimate contact with coke; and, when the ore particles are later disintegrated by the expulsion of their zinc con tent during the distillation the gaps left in the structure are as small as possible, so that the strength of the residue is preserved, However, such free-flowing coals as a rule swell or puff up when heated to coking term peratures, and are then known as swelling coals. This property of swelling is undesirable in the preparation of coked agglomerates of zinc ore and coal, since the swelling tends to split up the agglomerates during the coking operation. This tendency of the swelling free-flowing coal to split up the briquettes is,

according to, the present invention, overcome and coke breeze or the like may advantaoal of bituminous rank mined from the Pittsburg seam of the Monongahela series in the Preston-Taylor mining district, Taylor County, West Virginia, is a high volatile free-flowing and swelling coal of excellent coking quality. Agglomerate mixtures of about roasted'zinc flotation concentrates and 50% of this coal, when briquetted and coked, flow and swell during coking, and the resulting coked agglomerates stick together and are objectionably distorted and ruptured, although of very satisfactory strength. By appropriately blending the above-described free-fiowing and swelling coal with a non-swelling oiz shrinking coal, :1 very satisfactory carbonaceous mixture for coked agglomerates may be produced. Thus, with the 5050 mixture of ore and reduction fuel, we have secured satisfactory results with a blend of from 20-10% of the abovementioned free-flowing and swelling coal and from 3040% of coal of bituminous rank mined from the Pittsburg seam of the Monongahela series in the Connellsville mining district, Fayette County,'Pennsylvania, a very slightly swelling coal'of good coking quality. This blend is further improved by substituting anthracite coal dust, coke breeze, or similar non-coking carbonaceous material, for a small percentage of the coking coals. Thus, we have secured excellent results with the following agglomerate mixture.

Per cent by weight Zinciferous material 55. 5 Preston-Taylor coal 18.5 Connellsville coal 18.5

Anthracite dust coal 7. 5

As a representative standard foran agglomerate mixture of parts of zinciferous material and 40 parts of carbonaceous material, we have found the following proportions one of general application:

Per cent by weight Zinciferous material 60 Free-flowing coal of good' coking quality- 15 Non-swelling coal of good coking quality- 25 Tower Hill coal evidence this tendency to swell, and in such cases we have secured satisfactory results with the following mixture:

Per cent v by weight Roasted zinc flotation concentrates 61. 5

Preston-Taylor coal 11. 5

Connellsville coal 19 Anthracite dust coal 8 We have furthermore secured satisfactory results with the following blend of a swelling coal of good coking quality and anthracite dust coal Per cent by weight Roasted zinc flotation concentrate 60 Preston-Taylor coal 30 Anthracite dust coal 10 treatment in the edge-runner, as well as the capacity of compacting thus brought about.

Optimum results appear to be secured when the bituminous coking coal is of a graded size with not more than about 16% on a 14 mesh screen and not more than about 16% through a 200 mesh screen, the remaining 68% displaying a substantially uniform gradation of size. The following data may be considered for illustrative purposes:

Table No. I

Hammer mill crushed cu- Bituminous coal mulative 0n 8 mesh screen 4.3 through 95.7 14 mesh screen 11.8 83.9 -20 mesh screen 10.6 73.3 28 mesh screen 9.6 63.7 35 mesh screen 11,8 51.9 48 mesh screen 8.9 43.0 65 mesh screen 7.5 35.5 80 mesh screen 3.6 31.9 mesh screen 4.6 27.3 150 mesh screen 5.8 21.5 200 mesh sc een 5.0 16.5 Through 200 mesh screen 16.5

It is desirable, but not necessary, that the non-coking carbonaceous material of the agglomerate mixture be of the aforementioned graded particle size, and the closer this is approximated the more closely'will the eoked agglomerates approximate the optimum desired properties; We have, however, successfully used for the non-coking carbonaceous material of the foregoing mixes coke crushed to pass through 8 mesh.

Optimum results appear to be secured when the zinc ore, if roasted, is of a graded size with not more than about 4.0% on a 14 mesh screen and not more than about'38% through a 200 mesh screen,

the remaining 58% displaying a continuous gradation of size, with gradual increase in the weight of material through the finer screens. The following.

data may also be considered for illustrative purposes Table No. I]

Roasted flotation concentrates cumulative On 8 mesh screen 1.9 through 98.]

14 mesh screen 1.3 96.8

20 mesh screen 0.7 96.1

28 mesh screen 0.5 95.6

35 mesh screen 0.9 94.7

48 mesh screen 1.3 93.4

65 mesh screen 2.8 90.6

80 mesh screen 4.1 86.5

100 mesh screen 10.9 75.6

150 mesh screen 18.9 56.7

200 mesh screen 19.3 37.4 Through 200 mesh screen 37.4

In the case of unroasted zinc ores, such as zinc silicate (Willemite), it appears that the particles may be substantially coarser, as indicated by the following illustrative data:

Table No. [II

Unroasted zinc silicate willemite ore The particle size of the mixture of ore and coal after treatment in the edge-runner is also of'importance. The chased material should have a particle size that is consistent with the formation of an agglomerate of optimum or at least adequate coking and residue strengths. Thus, if the particle size of the chased material is too fine, the agglomerates will be relatively dense and compact. During the subsequent'coking and/or reduction operations, the volatile constitutents will escape from the agglomerate with extreme difficulty,-if at all. In order to drive the volatile hydrocarbons and zinc from the agglomerate, considerable pressure will be set up within the agglomerate. Stresses and strains take place within and the agglomerate works away from therefore harmful, and should be avoided.

On the other hand, the chased material is too coarse, the agglomerates will not be as dense and compact as they should be to insure adequate, let alone optimum, coking and residue strengths. In other words, there appears to he a happy mean of particle size for the chased material which is compatible with the formation of an 'agglomerate that will have optimum coking and residue strengths. The following tables. give data that may be regarded as illustrative of this point, as par will usually rupture and disintegrate. Such a result porosity of the charge, is

if the particle size of.

adequate or Chased mix rved 60 roasted fl tation 3O Preston-Taylor coal 10 anthracite coal with respect to certain v mixtures of zinc ore and coals:

Table IV consisting of concentrates on cumulative On 8 mesh screen 1.2 through 98.8 14 mesh screen 4.9 93.9 20 mesh screen 4.5 89.4 28 mesh screen 3.8 85.6 35 mesh screen 51 80.5 48 mesh screen 3.5 77.0 V mesh screen 3.4 73.6 80 mesh screen 1.8 71.8 100 mesh screen 2.2 69.6 150 mesh screen 4.0 65.6 .200 mesh screen 4.2 60.8 Through 200 mesh screen 60.

Table V Chasedmix consisting of:

50 roasted flotation concentrates 20 PrestolrTaylor free flowing coal 30 Conneilsville slight swelling coal on cumulative On 8 mesh screen .6 through 99.4 14 mesh screen 3.4 96.0 20 mesh screen 5.8 90.2 28 mesh screen 5.7 84.5 35 mesh screen 7.6 76.9 48 mesh screen 6.9 65 mesh screen 8.6 61.4 0 mesh screen 5.2 56.2 100 mesh screen 6.1 50.1 150 mesh screen 8.4 41.7 200 mesh screen 6.6 35.1 Through 200 mesh screen 35.1

Table VI Chased mixconsisting of:

61.5 roasted flotation concentrates 11.5 Preston-Taylor free flowing 8.0 anthracite dust coal 19.0 Connellsville slight swelling coal on cumulative On 8 mesh screen .4 through 99.6 14 mesh screen 2.0 97.6 20 mesh screen 2.5 95.1 28 mesh screen 2.2 92.9 35 mesh screen 3.8 89.1 48 mesh screen 8.] 86.0 65 mesh screen 3.0 83.0 mesh screen 2.0 81.0 100- mesh screen 2.7 78.3 150 mesh screen 5.6 72.7 200 mesh screen 5.6 67.1 Through 200 mesh screen 67.1

Table VI] Chased mix consisting of:

60 nnroasted silicate ore 20 anthracite dust coal 20 Preston-Taylor free flowing and swelling coal 150 200 Through 200 mesh mesh mesh mesh mesh mesh mesh mesh m sh mesh mesh mesh The graded particle size of the ingredients 0 the agglomerate mixture, the present invention, of the mixture as will contemplated by insures such density give adequate if not maximum strength of the coked agglomerate.

This graded particle size furthermore promotes the desired intimate mixture of the zinciferous and ca rbonaceous materials and insures better compacting of these materials by briquetting, extrusion and like operations.

' tion are usually made up from 35 to 65% by weight of zinciferous material and from 65 to 35% by weight of carbonaceous material. ,In general, the higher the zinc content and the more finely divided the zinciferous material, the more coal will be needed in the mixture. The examples given above illustrate the manner in which the proportions of coals may be suitably blended when worked with certain ZlIICifBIOllS materials, and the relation of the total'coal content to the ore, in order to secure very favorable results. It will, of course, be understood that the examples and tables given above are to be regarded as illustrative, rather than restrictive, of the invention. It is altogether possible that some variations of the figures herein referred to are necessary to secure optimum results under other and varied circumstances, such as in the type of coals and/or ores employed. The principles of the present invention are, however, applicable in such situations.

The chased material is then suitably agglomerated. For this purpose it may be advisable to use a binder in appropriate amounts. The agglomerates may be formed in various sizes and shapes and with varying degrees of density and compactness. uch factors as size, shape and density of the agglomerates will be largely governed by the particular coking and reduction operations to be employed. Other conditions being equal, the longer the column of agglomerates placed'in a coking and in a reduction retort, the stronger should be the agglomerates near the bottom of the column to avoid breaking down by compressive forces. Any suitable ap aratus may be employed for both the co ing and reduction operations. In the' present preferred practice of the invention,. the agglomerates are coked by direct heating 7 and the coked agglomerates are then smelted for the recovery of their zinc content in an externally heated vertical retort.

We claim:

1. The method of preparing coked agglomerates of zinciferous material and carbonaceous material which comprises intimately mixing the zineiferous material, with the carbonaceous material the carbonaceous materialcontaining from 15 to %by weight with respect to the total weight of the mixture of a free-flowing and swelling coal of good coking quality, forming the resulting mixture by pressure into agglomerates, and subjecting the agglomerates to a coking operation.

2. The method of preparing coked agglomerates of zinciferous material and carbonaceous material which comprises intimately mixing from to by weight of the zinciferous material with from 65 to 35% by Weight of carbonaceous material, the carbonaceous material being made up of from 15 to 25% by weight with respect to the total weight of the mixture of a free-flowing and swelling coal of good coking quality, forming the resulting mixture by pressure into agglomerates, and subjecting the agglomerates to a coking operation. I

3. The method of preparing coked agglomerates of zinciferous material and carbonaceous material which comprises intimately mixing the zinciferous material with the carbonaceous material, the carbonaceous material being made up of a mixture of a free-flowing and swelling coal of good coking quality and the balance of a substantially non-swelling coal, forming the resulting mixture by pressure into agglomerates, and subjecting the agglomerates to a coking operation.

4. The method of preparing coked agglomcrates of zinciferous material and carbonaceous material which comprises intimately mixing the zinciferous material with the carbonaceous material, the carbonaceous material being made up of a blended mixture of coking coals, consisting of free-flowing-swelling and slightly swelling coals, forming the resulting mixture by pressure into agglomerates, and subjecting the agglomerates to a coking operation.

5. The method of preparing coked ag lomerates of zinciferous material and car onaceous material which comprises intimately mixing the zinciferous material with the carbonaceous material, the carbonaceous material being made up of a blended mixture of coals that will be substantially non-swelling consisting of free-fiowing-swelling, swelling and non-swelling coals of good coking quality, forming the resulting mixture by pressure into agglomerates and subjecting the agglomerates to a coking operation.

6. The method of preparing coked ag 'lomerates of zinciferous material and car onaceous material which comprises intimately mixing the zinciferous material with the car bonaceous material, the carbonaceous material being made up of from 15 to 25% by weight with respect to the total weight of the mixture of a free-flowing and swelling coal of good coking quality and the balance of anon-coking carbonaceous material, forming the resulting mixture by pressure into agglomerates, and subjecting the agglomerates to a coking operation.

7 The method of preparing coked agglomcarbonaceous material crates of zincifcrous material and carbonaceous material which comprises intimately mixing the zinciferous material with the carbonaceous material, the carbonaceous material being made up of about equal parts by weight of a free-flowing and swelling coal of good coking quality and ,a non-coking carbonaceous materia, forming the resulting mixture by pressure into agglomcrates, and subjecting the agglomcrates to a coking operatic 8. The method of preparing coked agglomerates of zincifcrous material and carbonaceous material which comprises intimately mixing the zinciferous material with a blended carbonaceous material containing substantial proportions of a free-flowing and swelling coal of good coking quality and a non-coking carbonaceous material, forming the resulting mixture by pressure into agglomerates, and subjecting the agglomerates to a coking operation.

9. The method of preparing coked agglomerates of zinciferous material and car-- onaceous material which comprises intimately mixing the zinclferous material w1th of a free-flowing and swelling coal of good coking qualityof such particle size that not more than about 16% is on 14 mesh and not more than about 16% is through 200 mesh, forming the resulting mixture by pressure into agglomerates, and subjecting the agglomerates to a coking operation.

10. The method of preparing coked agglomeratcs of zinciferous material and carbonaceous material which comprises intimately mixing the zinciferous material with carbonaceous material made up in large part of a free-flowing coal of good coking quality of such particle. size that at least by weight is graded between 20 and 100 mesh and not more than about 16% by weight is through 200 mesh, forming the resulting mixture by pressure into agglomerates, and subjecting the agglomerates to a coking operation, i

11, The method of preparing coked agglomerates of zinciferous material and carbonaceous material which comprises intimately mixing the zinci'terous material with carbonaceous material, said carbonaceous material consisting in part of bituminous free-flowing and swelling coal of a particle size adapted to give a screen analysis of not more than about 18% on a M mesh screen and not more than about 16% through a 200 mesh screen, the material passing through a 14 mesh screen and remaining on a 200 mesh screen displaying a substantially uniform gradation of size, and in part of a non-swelh ing coal adapted to off-set the swelling effects of said free-flowing and swelling coal, forming the resulting mixture by pressure into made up in largepart agglomerates, and subjecting the agglomerates to a coking operation.

12; The method of preparing coked age glomerates of zin'ciferous material and carbonaceous material which comprises intimately-mixing the zinciferous material with carbonaceous material, said carbonaceous material consisting of a blended mixture of coals adapted to give a good coking efi'ect without substantial swelling, said zinciferous material consisting of roasted zinc ore of a particle size adapted to give a screen analysis of not more than about 4% on a 14 mesh screen and not more than about 38% through a 200 mesh screen, the material passing through a 14 mesh screen and remaining on a 200 mesh'screen displaying a substantially uniform gradation of size, forming the resulting mixture by pressure into agglomerates, and subjecting coking operation.

13. The method of the agglomerates to a preparing coked agglomerates of zinciferous material and carbonaceous material which comprises intimately mixing the zinciferous material with carbonaceous material, said carbonaceous material consisting in part, of bituminous free-flowing and swelling coal of a particle size adapted to give a screen analysis of not more than about 16% on a ll mesh screen and not more than about 16% through a 200 mesh screen, through a 14: mesh'screen and remaining on a 200 mesh screen displaying'a. substantially uniform gradation of size, and in part of a non-swelling coal adapted to off-set the swelling efi'ects of said free-flowing and swelling coal, said zinciferous material consisting of roasted zinc ore of a particle size adapted to give a screen analysis of not more than about i 0 on a let mesh screen and not more than about 38% thrgugh a 200 mesh screen, the remaining 58% displayin a sub stantially uniform gradation of size, orming the resulting mixture by pressure into ag-- glomerates, and subjecting the agglomerates to a coking operation;

14.. Thernethocl of preparing coked agglomerates of zinciferous material and car-' bonaceous material which comprises inti mately mixing the zinci'ferous material with blended carbonaceous material adapted to yield a mass of good coking but substantially non-swelling qualities, kneading and grinding together said material until the resulting mixture is composed-of particles adapted to give a screen analysis of not more than about 10% on a 14 meshscreen and not more than about ing the resulting mixture by pressure into agglomerates, and subjecting the agglomerates to a coking operation.

the material passing through a 200 mesh screen, formmately mixing the zinciferous material with 'Icarbonaceous material, said carbonaceous material consisting in part of bituminous free-flowing and swelling coal of a particle size adapted to give a screen analysis of not more than about 16% on a 14 mesh screen and not more than about 16% through a 200 mesh screen, the material passing through a 14 mesh screen and remaining on a 200 mesh screen displaying a substantially uniform gradation ofsize, and in part of a non-swelling coal adapted to off-set the swelling eflects of said free-flowing and swelling coal, said zinciferous material consisting of roasted zinc ore of av particle size adapted to give a screen analysis of not more than about 4% on a 14 mesh screen and not more than about 38% through a 200 meshscreen, the material passing through a 14 mesh screen and remaining on a 200 mesh screen displa ing a substantially uniform gradation o s1ze,

kneading and grinding together said materials until the resulting mixture is composed of particles adapted to give a screen analysis of not more than about 10% on a 14 mesh screen and not more than about through a 200 -mesh screen, forming the resulting mixture by pressure into agglomerates, and subjecting the agglomerates to a coking operation.

In testimony whereof we afiix our signatures.

EARL H. BUNCE. .THOMAS C. RQUTSON.