US2465955A - Process for the treatment of fluorspar - Google Patents

Description

Patented Mar. 29, 1949 PROCESS FOR THE TREATMENT OF FLUORSPAR John Norman Wynne, Glyn Ceiriog, near Wrexham, North Wales No Drawing. Application June 12, 1945, Serial No. 599,131. In Great Britain January 12, 1944 4 Claims.

This invention relates to the production of fiuorspar in a form suitable for metallurgical and other purposes from fluorspar concentrates.

Such concentrates are generally produced by froth flotation or other process in the form of finely ground natural fiuorspar by which treatment a large proportion of the silica is separated from the calcium fluoride, and powdered concentrates are obtained containing varying percentages of calcium fluoride and silica classifying them as, metallurgical, ceramic and acid grades of fiuorspar containing for example about 8%, 2% and 0.5% of silica respectively.

The powdered metallurgical grade is not suitable for operations such as steel production but it has been suggested for this purpose to mix the powdered product with a suitable binder and press or mould it into briquettes or the like.

However, briquettes formed in this way are costly to produce apart from the fact that the binder may introduce undesirable additions to the fiuorspar, and for this reason steel manufacturers prefer to use native fiuorspar appropriately graded as to size, for example grave It has now been found that the difficulties of using fiuorspar concentrates can be overcome if, according to the present invention, the concentrates are subjected to heat treatment which effects bonding of the particles to agglomerates of the desired size without altering the chemical or physical properties of the concentrates and without the employment of binding agents.

For example if the concentrates are subjected to a temperature of about 1100 C. for a period of about 20 minutes a suitable agglomerate for the manufacture of steel and other purposes is produced. The temperature may be lower and the heating period may be varied, to suit different sized particles comprising the concentrate. A temperature range of about 1000 C. to about 1100 C. has been found satisfactory.

The period of the heat treatment will depend upon the thickness of the layer of material treated.

In one way of carrying the invention into effect a fire-clay or other suitable mould is employed for example in the form of a tray, pan or pallet the face of which is provided with a number of recesses of the desired shape and size of the finished agglomerate. The cavities are filled with the powdered concentrate and subjected to the heat treatment as above described and the agglomerates are removed from the mould after the latter has cooled.

The recesses in the mould may be of any convenient shape such as gravel, pellets, lozenge, cube or slab, or series of such shapes.

In another way of carrying out th invention a belt of suitable heat resistant material may be employed provided With or Without recesses, which are filled with the powdered concentrate by any convenient means, the belt then passing through a kiln, muiile or the like so that the concentrates are subjected to the gradual heat treatment as above described. The finished agglomcrates are delivered in a suitable form for transport and subsequent use for example in the manufacture of steel. Or the concentrate may be filled into any sized crucible or agglomerated into any sized masses which may later be broken into suitably sized pieces.

It is desired to point out that the heat treatment which effects agglomeration is not such as to cause fusion of the fluorspar as will be evident from the temperature employed.

I claim:

1. The process of manufacturing agglomerated pieces of fiuorspar suitable for metallurgical and similar purposes comprising heating finely divided fiuorspar concentrate having as essential impurity less than about 8% of normally high fusing silica and free of low fusing impurities having a bindive effect to a temperature below the fusion point of the constituents of the fiuorspar in the range of approximately 1000 to 1100 C. for a short period of time and without addition of extraneous binder materials.

2. The process of manufacturing agglomerated pieces of fiuorspar suitable for metallurgical and similar purposes comprising heating finely divided fiuorspar concentrate having as essential impurity less than about 8% of normally high fusing silica and free of low fusing impurities to a temperature below the fusion of the constitutents fiuorspar of about 1100 C. for a short period of about 20 minutes and without addition of extraneous binder materials.

3. The process of agglomerating mineral fiuorspar concentrate having as essential impurity less than about 8% of normally high fusing silica and free of low fusing impurities and without addition of extraneous binder materials comprising filling the concentrate into molds and heating the molds to a temperature below the fusion point of the constituents of the fluorspar in the range of approximately 1000 to 1100 C. for a short period of time.

4. The process of agglomerating mineral fluorspar concentrate having as essential impurity less than about 8% of normally high fusing silica and free of low fusing impurities and Without addition of extraneous binder materials comprising passing the fiuorspar on a belt through a heating zone maintained at a temperature to heat the iiourspar below the fusion point of its constituents in the range of approximately 1000 to 1100 C. for a period of approximately 20 minutes;

JOHN NORMAN WYNNEQ REFERENCES CITED The following references are of record in the file of this patent:

5 UNITED STATES PATENTS Number Name Date 338,924 Carson Mar. 30, 1886 1,792,413 Christiansen Feb. 10, 1931 10 2,184,078 Hyde Dec. 19, 1939 2,220,383 Abbot Nov. 5, 1940 2,220,385 Abbot Nov. 5, 1940 FOREIGN PATENTS g 5 Number Country Date 5,293 Great Britain 1909 OTHER REFERENCES Chemical Abstracts, 1933, vol. 27, pp. 3865, paragraph 6.