C, R, KUAE PR0 (CESS OF MANUFACT UR | N G | TH 0P 0 N E À PPLICATION FILED AUG, 15, 1921, 1,399,500. Patented Dec, 6, 1921.

UNITED STATES PATENT OFFICE. CHEARTES. R. E.U2ELE, OF CLARKDALE, ARIZONA. SLLaLLLLLLL0LLLL GLLLLS LLLLLLLYLLLLLLLY LLLL LLLLLLLLS LLLGLLGGLGLLYS 1,399,500. specification of Tetters Patent, latented Dec. 6, 1921. Application filed August 15, 192i. Serial No. 492,342. ?? ??? ?????? ?? ???? ???????"?, these tanks) in which the crude lithopone Be it known that II, CHARLES R. KUZELL, is allowed to thicken by settling until it is a citizen of the United States, residing at concentrated to a Suitably dense pulp after Clarkdale, in the county of Yavapai and which it is drawn off by a high pressure 60 State of Arizona, have invented certain new pump 2 and discharged through suitable and useful Improvements in Processes of Spray nozzles 3 into a desiccating chamber 4 Manufacturing Lithopone, of which the fol through which the fine snray is carried by lowing is a specification. a current of air admitted to the chamber 4. My invention has relation to improve through a spray head 5 terminating the air 65 ments in the manufacture of lithopone, the Supply conduit 6. The air current and the process of which consists in the novel com finely divided lithopone are thoroughly bination of steps more fully set forth here mixed in the desiccating chamber, the latter inafter. . . . . being carried through the chamber by the The object of the present invention is to air current, which dries the lithopone as it 70 15 simplify the present method of manufac is carried through the chamber. The dried ture of lithopone by eliminating all the lithopone is discharged from the chamber steps subsequent to the precipitation of 4 through a conduit 7 communicating with crude lithopone, and substituting fewer and an electrical precipitation chamber (such simpler steps whereby less plant equipment electrical recipitation being generally 75 20 is required and consequently a reduced cost known as the Cottrell process) where the of operation is accomplished. lithopone held in suspension by the air Lithopone is a white paint pigment and current is precipitated as an extremely consists in a mixture of substantially 70% finely divided powder and in finished con barium sulfate and 30% zinc sulfid although dition. The finely divided lithopone may 80 25 commercially these proportions valry greatly also be collected in a bag house such as is and the lithopone is sold under names that used for collecting the mineral particles indicate the grade. from furnace fume. Briefly the process of manufacture up to As is Well known, lithopone has the prop the precipitation of crude lithopone may be erty of darkening when exposed to the 8 (0 described as follows, reference being had light, and various processes have been 85 to the accompanying drawing showing a evolved with a view of preventing this. flow sheet illustrating the usual practice up This darkening is caused by a reduction of to the precipitation of crude lithopone and the zinc sulfid to metallic zinc and the only the subsequent steps of dehydration and Way to prevent it is by providing a pro 90 35 preparation which constitute my improve tective film over the zinc sulfid. I accom ment : , plish this as follows: Barytes is reduced with coal in a suit The air discharged into the chamber 4 is able furnace and a clear solution of barium heated not only to dry the lithopone but sulfid obtained by lixiviation of the black also cause a superficial oxidation of the zinc 95 40 ash with hot water. The barium sulfid solu sulfid according to the equation ZnS-3O= tion is added to a purified solution of zinc ZnO--SO. sulfate (obtained in any well known man The ZnO forms a protective film around ner such as treating a zinc material with the ZnS and thus prevents darkening of the sulfuric acid) whereupon the crude litho lithopone when exposed to the light. The 00 pone is precipitated. Now, under the pres temperature of the heated air is just suffi ent practice this crude lithopone is sub cient to oxidize the sulfid not to exceed from jected to a number of operations before the 3% to 5% of zinc oxid in the finished litho finished product is obtained such as filter pone, the composition of which would then ing, drying, calcining, quenching in Water, be substantially 105 50 grinding, etc., all of which require equip ment and take time to perform. I have Barium sulfate------68% greatly simplified the refining of le crude Zinc sulfate------28% lithopone as will be better apparent from Zinc oxid------4% what follows. a very good grade of lithopone that will 0. 55 Referring to the drawing, 1 represents a not darken on exposure to the light. settling tank (there may be a number of Having described my invention, I claim: 2 1. The hereindescribed method of prepar lithopone from a mixture of barium sulfid ing lithopone which consists in precipitat and zinc sulfate, discharging the liquid con ing crude lithopone from a mixture of bari taining crude lithopone as a fine spray into um sulfid and zinc sulfate solutions, permit a current of heated air whereby the zinc 40 ting the liquid containing crude lithopone sulfid constituent of the lithopone will un to thicken by settling, thereafter spraying dergo a partial Superficial oxidation and the liquid into a drying chamber in contact thereafter collecting the finished product as with air, and precipitating the lithopone as a finely divided powder. a fine powder. 6. The process of manufacturing litho 45 10 2. The process of manufacturing litho pone which consists in precipitating crude pone which consists in precipitating crude lithopone from a mixture of barium sulfid lithopone from a mixture of barium sulfid and zinc sulfate solutions, permitting the and zinc sulfate solutions, drawing off the liquid containing crude lithopone to thicken liquid containing crude lithopone and dis by settling, discharging the thickened liquid 50 15 charging the same as a fine spray into a cur as a fine spray into an oxidizing atmosphere rent of air whereby it will be dried as a fine heated sufficiently to cause partial superfi powder and collecting the powder so formed. cial oxidation of the zinc sulfid ingredients, 3. In the manufacture of lithopone, the and thereafter collecting the finished prod process which comprises the precipitation of uct as a finely divided powder. 55 20 crude lithopone from a mixture of barium 7. The process of manufacturing litho sulfid and zinc sulfate solutions, thickening pone which consists in precipitating crude the precipitated lithopone by settling, draw lithopone from a mixture of barium sulfid ing off the liquid so thickened and discharg and zinc sulfate solutions, permitting the ing the same as a fine spray into a drying liquid containing crude lithopone to thicken 60 25 chamber and thereafter collecting the litho by settling, discharging the thickened liquid pone as a finely divided powder. as a fine spray into an oxidizing atmosphere 4. In the manufacture of lithopone, the heated sufficiently to cause partial superfi process which comprises the precipitation of cial oxidation of the zinc sulfid ingredients, crude lithopone from a mixture of barium and thereafter conducting the dried litho 65 30 sulfid and zinc sulfate solutions, drawing off pone to an electrical precipitation chamber the liquid and discharging the same as a fine where the lithopone is precipitated as a finely spray into a drying chamber and thereafter divided powder. collecting the lithopone as a finely divided powder. signature.In testimony whereof I hereunto affix my 35 5. The process of manufacturing litho pone which consists in precipitating crude CHARLES , R. KUZELIL.