US1803611A - Zinc condenser - Google Patents

Description

Patented May 5, 1931 UNITED STATES PATENT OFFICE HARRY A. GRINE, OF CLABKSBUBG, WEST VIRGINIA, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO THE GBASSELLI CHEMICAL COMPANY, OF CLEVELAND, OHIO, A CORPORA- TION OF DELAWARE ZINC CONDENSER Ho Drawing.

The present invention relates to the lining of zinc condensers and more particularly to the rovision of a lining which is readily separa le together with incrustations of zinciferous material from the body of the condenser.

Zinc commonly is produced by direct reduction of its ores with volatihzation and condensation of the zinc. For instance, ac-

cording to the Belgian retort system, a mixture of roasted zinc ore and a reducin agent is charged into a cylindrical horizonta retort and the retort is then externally heated to a temperature of about 900 C. to 1000 C. un-

der exclusion of air until the reduction and volatilization of the zinc content of the ore is effected. The zinc vapor passes to a condenser which is usually made of a refractory material and which is joined to the discharge end of the retort by a suitable cementing material such as fire clay or anthracite culm. The shape and dimensions of the zinc condenser are subject to variation. However, the condenser used in the Belgian retort system referred to above is usually a tube of le shape or conical form and about two feet in length. The zinc vapor is cooled and condensed in the condenser into fluid metal and is tapped therefrom into receiving ladles.

In the production of zinc by processes of the character described above, there has been found to be a strong tendency for the fluid zinc to soak into the walls of the condenser and to form a strongl adhering coating or in- 5 crustation thereon. This coating is a kind of superficial skull keyed into the surface pores of the condenser wall with the exception of about 1 at the butt end of the condenser where it projects into the retort month, where 133 zinc is actually absorbed in the condenser 13 present practice, the zinc thus absorbed or attached to the condenser walls has been partially recovered by breaking at least that portion of the condenser having a heavy coat- Application flied May 25, 1927. Serial No. 194,288.

ing of metallic zinc, blue powder and oxide, into small pieces and chargin these pieces into the blue powder section 0 the furnace. Due to the strong adherence of the zinc-bearing material to the condenser wall, it is impractical to separate the zinc-bearing material therefrom, mechanically, unless this is done in an ore concentrating apparatus, such as a wet concentration mill, but due to the small tonnage involved, this is not economical. Consequently, the recovery of the zinc from the nose end of the condenser which has only a relatively light coating of zinc-bearing materials, is impractical from an economical standpoint by the above method and this portion of the used condenser is usually discarded and its zinc content lost.

The principal object of the present invention is the provision of an improved form of zinc condenser, whereby the zinc adhering to the walls thereof may be easily and economically recovered comparatively free from admixture with the refractory material from the condenser. 7

According to the present invention, the surfaces of the zinc condenser upon which condensation occurs are provided with a thin lining of a refractory material which may be easily separated mechanically from the condenser walls but which possesses sufiicient bondin strength to maintain a thin shell between t e inner walls of the main body portion of the condenser and the layer or skull of zinc-bearing materials formed during the distillation operation.

The following example illustrates the preferred embodiment of my invention, it being understood that the invention is not to be limited to the particular condenser or method of forming the same described therein except as is required by the claims annexed hereto.

A lining material is prepared from the I shells of previously used condensers by grinding the same preferably so as to pass a. Tyler screen of 20-mesh or finer, and mixing the finely ground material with sufficient water to give a mortar having about the consistency of (lip mortar for firebrick. A mix containing 10 parts by volume of water to 17 parts by volume of the finely ground condenser shells has been used with good results. A lining of this mixture preferably having a thickness of about th to is provided upon the surface of the condenser upon which deposition of the zinc-bearing material ocours.

The lining mix prepared of the ingredients and in the proportions described above gives a particularly advantageous lining since it has the necessary internal bonding strength but may be easily separated from the inner walls of the condenser shell. The low degree of adhesion between the lining and condenser shell may be attributed to the fact that the raw clay present in the mixture of raw clay and burnt grog from which the condenser was originally formed becomes partially burned in use and loses much of its adhesiveness. A further advantage of this material is that it is practically free from shrinkage and the lining formed therefrom does not crack or chip on drying. If desired, various other refractory materials having the required internal bonding strength coupled with low adhesiveness with respect to the refractor shell of the condenser may be substitute for the finely ground previously used condenser shells.

The lining may be formed of two coats, if desired. For example, a lining formed by first coating the condenser shell with a mix containing a refractory material obtained from furnace tops ground to 100 mesh, and then with a mix formed from the previously used condenser shells as described above, has been used with good results.

The term furnace tops as referred to above is colloquially used to designate the dust which settles on top of the zinc furnaces during operation. This dust is composed of zinciferous material mixed with coal particles and other mineral matters which always float in the atmosphere around the furnaces, and from which zinc is usually recovered by adding this dust to the smelting charge.

Various methods may be used for applying the wet mixture of lining material as, for instance, by brushing or swabbing. However, the present invention contemplates a particularly advantageous method of applying the lining material wherein a relatively large quantity of the wet lining mix is brought into contact with the condensing surfaces and then allowed to drain freely therefrom. This method results in the formation of a thin uniform coating which after drying gives a lining having a comparatively sharp plane of cleavage with the walls of the condenser and consequently is easily separated therefrom.

The preferred method for lining the condenser may be practiced, for example, by completely filling the condenser with the wet mix of lining material and then pouring out the surplus material, thereby forming a coating. The thickness of the coating may be varied, for instance, by varying the consistency of the wet mix or by applying a plurality of coatings. This method may be conveniently applied by standing the condenser on a rack, nose end downward, a suitable pad, for instance, felt, being interposed between the rack and the condenser to close the lower opening thereof. A suitable vessel is placed below the rack to catch the surplus coating material. The condenser is filled with the wet mix and is then lifted from the pad and the excess material permitted to run into the drainage vessel. In large scale operation, the coating material preferably is handled by means of a pump so that the condenser may be filled from a hose.

After the coating of lining material has been applied, the condenser is set aside and the lining allowed to dry thoroughly before use. The lining formed, as described above, has been found to dry quickly without checking or peeling and is sufficiently strong to withstand the abrasions to which it is submitted during the first distillation operation while the skull of zinc-bearing material is forming and which subsequently protects the lining from abrasion.

Other linings such as made from crude refractory clay or from slaked lime can be applied to the retorts by this preferred method.

After the condensers have been used and discarded due to the formation of heavy zinc deposits or breakage, they are broken up by rapping with a hammer. During this procedure the skull of zinc-bearing materials formed in the condensers lined according to my invention separates freely from the main body portion or shell of the condenser; hence, the zinc-bearing material is recoverable in a form comparatively free of clay and hence much more suitable for metallurgical treatment than the inseparable mixtures of clay and zinc obtained heretofore, and likewise the broken condenser shell is left comparatively free from zinc and may be discarded or used for making new condenser shells or coating material or both.

I claim:

1. A zinc condenser comprising, in combination, a main body portion of a refractory material, and a refractory lining adhesively secured to the condensing surfaces of said main body portion but readily separable therefrom mechanically, said lining comprising a lightly burned mixture of raw clay and grog.

2. A zinc condenser comprising, in combination, a main body portion formed from a mixture of raw clay and grog, and a refractory lining comprising a lightly burned mixture of raw clay and grog.

3. A zinc condenser comprising, in combination, a main body portion of a refractory 5 material, and a refractory lining adhesively secured to the condensing surfaces of said main body portion but readily separable therefrom mechanically, said lining comprising finely ground previously used condenser 10 shells.

In testimony whereof I aflix my si ature.

- HARR YA.G INE.