Title of Invention

"A PROCESS OF BENEFICIATION OF PYROPHYLLITE FOR INCREASING BRIGHTNESS VALUE ABOVE 80"

Abstract

A process of beneficiation of pyrophyllite for increasing brightness value above 80 has been developed for its possible use in paper, paint, textile industries. At present these industries use essentially selected kaolinitic minerals, a 1:1 layer lattice mineral, the source of which is fast depleting. The process involves less consumption of chemicals as compared to that of kaolinitic mineral. The process is cost effective as kaoline is far more costly and the process of this invention adds value to the pyrophyllite making it suitable for more valuable use.

Full Text

The present invention relates to a process of beneficiation of pyrophyllite for increasing brightness value above 80. Pyrophyllite, a hydrous aluminosilicate finds use in white ware industries. Reference for which may be made to: (i) Chat Kit bay, " Pyrophyllite- the rare jewel of tile manufacture", Ceramic Industry, pp. 43-45 (Oct., 1998). (ii) Mishra, M.L. and Pathway, V. G. " Pyrophyllite from Hairpin in whiteware bodies". Trans. Ind. Cream. Soc., pp. 25-31, 19(1), (1960). (iii) Maiti K. N,, Prasad, C.S., Bandhopadhyay, S., "Investigation on the development of low maturing white stoneware body- Part II: Batch formulation incorporating non-conventional raw materials", proceedings of Annual Session of Indian Ceramic Society, (Feb., 1986). Pyrophyllite is also used in the field of asbestos products, insecticides as filler. Reference for which may be made to: Prasad C.S., Mukhopadhyay, T.K. and Maiti, K.N., "Characterization and utilization of some Indian pyrophyllites", Trans. Ind. Cream. Soc. pp. 96-105, Vol. 48-5(1989). However, around 20 - 30 % of deposited pyrophyllite is used in the field of ceramics and remaining portion is used as filler in pesticide, soap and insecticide industries due to inherent dullness of the materials and presence of ferruginous minerals as impurities. Removal of iron oxides from clay suspension by various chemical like hydrochloric acid, ammonium oxalate, sodium oxalate, sodium hydrosulphite or sodium bisulphite in presence of zinc dust at controlled pH was aimed by various research workers. Reference for which may be made to: (i) Tamm O., "Method for the estimation of the inorganic components of the gel complex in soils" Medd. Statens. Skogforsoksanst, pp. 385-404, 19(1922). Mitchell B. D. and Mackenjie R.C., "Removal of Iron oxides from clays", Soil Sci. pp. 173-184, 77(3) (1954). Guha S. K., Das S. R. and Sen Sudhir, " Chemical decolourisation of some Indian clays", Trans. Ind. Ceram. Soc., pp. 54-62, vol. 27(2)(1968). The minimum acceptable value of "brightness" for paper, paint and textile industries is 75. Reference for which may be made to Guha S. K., Das S. R. and Sen Sudhir," Chemical decolourisation of some Indian clays", Trans. Ind. Ceram. Soc., pp. 54-62, vol. 27(2)(1968). The main draw backs of the hitherto known prior art methods are: 1. High cost of the chemicals. 2. Complicated chemical process involved. 3. Prohibitive in respect of consumption of chemical or other accessories. 4. High cost of final product for use in paper, paint and textile industries. 5. Process is limited to Kaolinitic clay minerals which are essentially 1:1 layer lattice mineral. No work has so far been reported which deals with 1:2 layer lattice clay mineral such as pyrophyllite. Pyrophyllite is much cheaper than the conventionally used clay minerals. The main object of the present invention is to provide a process of beneficiation of pyrophyllite for increasing brightness value above 80. Another object of the present invention is to provide a process to increase the brightness of pyrophyllite for its use in industries such as paper, paint, textile and ceramics. Large deposits of pyrophyllite are available with rather limited use, at present. Brightness of this pyrophyllite is very low i.e., less than 50. Both clay and pyrophyllite have layer lattice structure. However clay is essentially 1:1 layer lattice mineral where one tetrahedral silica layer is attached with an octahedral alumina layer. Pyrophyllite on the other hand is 1:2 layer lattice mineral where one octahedral alumina layer is sandwiched between two silica layers. Most of the substitution occurs in this octahedral layer and Al+3 is mostly substituted by Fe+3. This makes the Fe+3 ions more firmly attached to the structure and can not easily be removed by chemicals. On reducing the particle size of pyrophyllite to the threshold limit, this 1: 2 alumino silicate layer lattice mineral may be made more reactive and structural iron is rather easily removed. In the present invention there is provided a process of beneficiation of pyrophyllite for increasing brightness value above 80, for its possible use in paper, paint, textile industries. At present these industries use essentially selected kaolinitic minerals, a 1:1 layer lattice mineral, the source of which is fast depleting. The process involves less consumption of chemicals as compared to that of kaolinitic mineral. The process is cost effective as kaoline is far more costly and the process of this invention adds value to the pyrophyllite making it suitable for more valuable use. Accordingly the present invention provides a process of beneficiation of pyrophyllite for increasing brightness value above 80, which comprises milling of crushed pyrophyllite lumps for a period in the range of 6 to 48 hours by conventional methods to obtain milled pyrophyllite, wherein the cumulative percentage of pyrophyllite particles finer than 10 µm is above 80% and the average particle size of the ground material is in the range of 4 to 6 µm, removing the elemental iron present in the milled pyrophyllite by conventional processes, treating the milled pyrophyllite with a leaching agent in the range of 1-5%, selected from a group of organic acids, inorganic acids, peroxides and borax for 24 to 60 hours to obtain a chemically leached milled pyrophyllite, filtering the chemically leached pyrophyllite to obtain a filter cake and washing with distilled water, drying the filter cake at a temperature in the range of 110 to 120 °C for a period of 12 to 48 hours. In an embodiment of the present invention leaching agent selected from inorganic acid is preferably hydrochloric acid in the range of 3-15% or sulphuric acid in the range of 1-5%, organic acid is preferably oxalic acid in the range of 0-10%, peroxides is preferably hydrogen peroxide in the range of 0-10% or borax in the range of 1-5%. When the fineness is increased by ball milling or pot milling with water, the brightness value of ground pyrophyllite may be increased upto the value of 68 which is due to the fact that by ball milling the average particle size of the milled material may be attained in the range of 18 to 20 µm. The ground pyrophyllite was again milled in vibro mill or attrition mill with water for 6 to 16 hours so that the fineness was increased and the cumulative percentage of particle finer than 10 µm was above 80% as well as the average particle size of the ground material varied between 4 to 6 µm. The brightness value of the above material was 78. When the above milled pyrophyllite was treated with 0 to 15% of hydrochloric acid, 0 to 5% of sulphuric acid, 0 to 10% of oxalic acid, 0 to 5% of hydrogen peroxide along with 0 to 5 % of borax and the material was left for 24 to 60 hours for ageing and finally filtered and washed with distilled water, the brightness value increased to 84. The main novelty of the process of the present invention lies in the starting material, pyrophillite. Further, the novelty of the present invention is to provide pyrophillite having increased brightness value above 80 which is used for paper, paint, textile, pottery, tiles, refractories and cement industries. The inventive steps which brings about the novel features of the present invention lies in reducing the particle size so that the cumulative percentage of particle finer than 10 µm was above 80% as well as the average particle size of the ground pyrophyllite varied between 4 to 6 µm to predetermined level followed by chemical leaching of ferruginous impurities present in the mineral. The details of the process steps of the present invention are given below: a) The deposited raw lump pyrophyllite was first jaw crushed. b) The crushed pyrophyllite of step 'a' was further milled by conventional processes such as pot milling, ball milling, vibro milling, attrition milling for 6 to 48 hours. s c) The elemental iron present in the milled pyrophyllite of step 'b' was removed by conventional processes. d) The particle size for the material collected from step 'c' was measured. The accepted cumulative percentage of the particle finer than 10 urn was above 80% and the average particle size of the milled material was 4 to 6 um. e) The material of step 'd' was now treated with 0 to 15% of hydrochloric acid, 0 to 5% of sulphuric acid, 0 to 10% of oxalic acid or 0 to 5% of hydrogen peroxide along with 0 to 5 % of borax and kept the slurry for 24 to 60 hours for ageing. f) Treated material of step 'e' was filtered and washed with distilled water, g) The washed material collected from step T was dried at 110 to 120°C for 12 to 48 hours. h) The brightness value of the dried material of step 'g' was measured. The following examples are given as illustration of the process of the present invention and should not be construed to limit the scope of the present invention. Example: 1 2 kgs of jaw crushed pyrophyllite sample was taken. The crushed material was further subjected to wet milling in pot for a period of 48 hours. The ground pyrophyllite was treated with 5% solution of hydrochloric acid and left for ageing for 24 hours. The slurry of chemically leached pyrophyllite so obtained was filtered and the filter cake was washed. The filter cake was dried at a temperature of 120°C for 24 hours. The brightness value of the milled and chemically leached pyrophyllite was found to be 72. Example 2 10 kgs of jaw crushed pyrophyllite sample was taken. The crushed material was further subjected to ball milling with water for a period of 36 hours. The ground pyrophyllite was passed through the electro magnetic separator and subsequently treated with 3% solution of hydrochloric acid and left for ageing for 24 hours. The slurry of chemically leached pyrophyllite so obtained was filtered and the filter cake was washed. The filter cake was dried at a temperature of 115°C for 24 hours. The brightness value of the milled and chemically leached pyrophyllite was found to be 8 kgs of jaw crushed pyrophyllite sample was taken. The crushed material was further subjected to pot milling with water for a period of 10 hours followed by vibro milling for a period of 10 hours. The ground pyrophyllite was subsequently treated with 3 % of hydrogen peroxide along with 1 % of borax for a period of 24 hours followed by addition of 2% solution of oxalic acid and left for ageing for 24 hours. The slurry of chemically leached pyrophyllite so obtained was filtered and the filter cake was washed. The filter cake was dried at a temperature of 110°C for 48 hours. The brightness value of the milled and chemically leached pyrophyllite was found to be Example 4 6 kgs of jaw crushed pyrophyllite sample was taken. The crushed material was further subjected to vibro milling alongwith water for a period of 6 hours. The ground pyrophyllite was subsequently treated with 1% solution of oxalic acid and left for ageing for 36 hours. The slurry of chemically leached pyrophyllite so obtained was filtered and the filter cake was washed. The filter cake was dried at a temperature of 110°C for 36 hours. The brightness value of the milled and chemically leached pyrophyllite was found to be 81. Example 5 500 gms of jaw crushed pyrophyllite sample was taken. The crushed material was further subjected to pot milling with water for a period of 10 hours followed by attrition milling for a period of 20 hours. The ground pyrophyllite was subsequently treated with 3% solution of oxalic acid and left for ageing for 36 hours. The slurry of chemically leached pyrophyllite so obtained was filtered arid the filter cake was washed. The filter cake was dried at a temperature of 110°C for 36 hours. The brightness value of the milled and chemically leached pyrophyllite was found to be Example 6 6 kgs of jaw crushed pyrophyllite sample was taken. The crushed material was further subjected to vibro milling with water for a period of 16 hours. The ground pyrophyllite was Passed through the electro magnetic separator and subsequently treated with 5 % of hydrogen peroxide along with 1.5 % of borax for a period of 24hours followed by 4 % solution of sulphuric acid and left for ageing for 48 hours. The slurry of chemically le*ached pyrophyllite so obtained was filtered and the filter cake was washed. The filter cake was dried at a temperature of 120°C for 40 hours. The brightness value of the milled and chemically leached pyrophyllite was found to 8 kgs of jaw crushed pyrophyllite sample was taken. The crushed material was further subjected to pot milling with water for a period of 10 hours followed by vibro milling for a period of 8 hours. The ground pyrophyllite was subsequently treated with 1.5% solution of oxalic acid and left for ageing for 36 hours. The slurry of chemically leached pyrophyllite so obtained was filtered and the filter cake was washed. The filter cake was dried at a temperature of 120°C for 36 hours. The brightness value of the milled and chemically leached pyrophyllite was found to be The main advantages of the process of the present invention are : 1. The process allows substitution of high cost material i.e., china clay, with a low cost low grade pyrophyllite. 2. Over all consumption of chemical is very low and process is less cumbersome. 3. No heat treatment is required, thus the process is energy efficient. 4. The final product has a variety of use in industries like paper, paint, textile, pottery, tiles, refractories and cement industries. WE CLAIM: 1. A process of beneficiation of pyrophyllite for increasing brightness value above 80, which comprises milling of crushed pyrophyllite lumps for a period in the range of 6 to 48 hours by conventional methods to obtain milled pyrophyllite, wherein the cumulative percentage of pyrophyllite particles finer than 10 µm is above 80% and the average particle size of the ground material is in the range of 4 to 6 µm, removing the elemental iron present in the milled pyrophyllite by conventional processes, treating the milled pyrophyllite with a leaching agent in the range of 1-5%, selected from a group of organic acids, inorganic acids, peroxides and borax for 24 to 60 hours to obtain a chemically leached milled pyrophyllite, filtering the chemically leached pyrophyllite to obtain a filter cake and washing with distilled water, drying the filter cake at a temperature in the range of 110 to 120 °C for a period of 12 to 48 hours. 2. A process as claimed in claim 1, wherein leaching agent selected from inorganic acid is preferably hydrochloric acid in the range of 3-15% or sulphuric acid in the range of 1-5%, organic acid is preferably oxalic acid in the range of 0-10%, peroxides is preferably hydrogen peroxide in the range of 0-10% or borax in the range of 1-5%. 3. A process for producing pyrophyllite having brightness value more than 80, substantially as herein described with reference to the examples.

Documents:

222-del-2003-abstract.pdf

222-DEL-2003-Claims-(23-10-2008).pdf

222-del-2003-claims.pdf

222-DEL-2003-Correspondence-Others-(23-10-2008).pdf

222-del-2003-correspondence-others.pdf

222-del-2003-correspondence-po.pdf

222-DEL-2003-Description (Complete)-(23-10-2008).pdf

222-del-2003-description (complete).pdf

222-DEL-2003-Form-1-(23-10-2008).pdf

222-del-2003-form-1.pdf

222-del-2003-form-18.pdf

222-del-2003-form-2.pdf

222-DEL-2003-Form-3-(23-10-2008).pdf

222-del-2003-form-3.pdf