Title of Invention

A PROCESS FOR THE PRODUCTION OF HIGH STRENGTH POROUS CERAMIC TILES UTILIZING INDUSTRIAL SOLID WASTES

Abstract

TITLE: A PROCESS FOR THE PRODUCTION OF HIGH STRENGTH POROUS CERAMIC TILES UTILIZING INDUSTRIAL SOLID WASTES. In the present invention, a process has been developed for the production of low cost porous ceramic tiles using waste materials like marble dust and fly ash, in combination with or without clay, by firing at temperatures below 1200°C. A marble dust fine, a waste material generated by the marble industries during cutting and polishing processes is used as a starting material. Another dreaded waste material, fly ash, mainly generated by the thermal power plant boilers, is also utilized. Formation of low temperature glassy phase on reaction between the constituent materials during firing is responsible for the strength development. The product produced by the present invention possesses bulk density in the range of 1.26 to 1.52 gm/cc, apparent porosity in the range of 36.5 to 47.5% and cold crushing strength in the range of 122 to 353 kg/cm2. Such type of high strength porous tiles can be used as insulating panels for the building industries.

Full Text

The present invention relates to a process for the production of high strength porous ceramic tiles utilizing industrial solid wastes. The present invention particularly relates a process for the production of high strength ceramic tiles utilizing industrial solid wastes namely marble dust and fly ash as major raw materials. The present invention is useful for the production of high strength porous ceramic tiles which has potential applications particularly in the building industry. The porous ceramic tile product produced by the present invention can be used in the floors and walls of office and residential buildings as insulating panel. Utilization or recycling if industrial wastes has been acclaimed world wide not only as an economic opportunity but also as a step to solve the most hazardous problems of environmental pollution. Marble dust is a dreaded solid waste material generated by the marble cutting industries. Around 50% of total marble mined is discarded as wastes in the form of marble slurry which is dumped in open fertile land. Fly ash is another solid waste material generated in huge quantities during combustion of coal in thermal power plant boilers. Both these waste materials have useful major inorganic constituents such as CaO in marble dust, AI2O3 and Si02 in fly ash. The inherent properties of which can be utilized in making useful value added newer products. Search of patents reveals a work of S. Li, K. De Groot, P.J.F Payroll, C.A. Blitterswijk (US Patent No. 6479418 dated Nov 12, 2002) wherein development of calcium phosphate based porous ceramic body is described using organic materials like wax, fats, shellac, fatly acid, resin, etc as pore former for the use as a scaffold for tissue. In another reference, US Patent No. 6057030 dated May 2, 2000, wherein T. Mano developed porous ceramic body for kiln furniture application based on alumina in association with lime, silica, titanic, zirconia’s, magnesia etc using polymethyl-methacrylate in yet another reference, US Patent No. 5834108 dated Nov. 10, 1998, wherein S. Shimai, K. Imura, I. Shibata, K. Okamoto, A Nizzuma and T Muto developed porous ceramic body from ceramic slurry. They foamed the slurry by agitation with the help of foam stabilizer ammonium stearate, binder methyl cellulose and dispersant poly ammonium acryl ate. In another reference, US patent No. 2002193234 dated 19th November 2002, wherein U, Miyao, K. Oda and N. Oda developed a porous sound absorbing ceramic body using 100 parts perlite, 100-200 parts sintered ceramic mat like fly ash, slag, chamote, silica, etc. and 10-20 parts of inorganic binder for pore development. Reference may also be drawn to A.P. Stavoyko, Inventor's certificate No. 220122, Byull, Izobret No. 19, 1968 and G.E. Karas, Ognenpory, No.9, 1972, wherein a light weight porous ceramic material was developed using a mix of uncalcined commercial alumina and saw dust. Another reference may be drawn to A. Pirogov, Ognenpory No. 5, 1978, wherein soluble methyl cellulose as surface active agent and saw dust as pore former was used for porous ceramic material. A literature reference may be drawn to P.K. Mondal, S.N. Mukherjee and G. Banerjee, Proceedings of Unitecr-95 Vol 2, pp 586-593, (1995), wherein micro-porous ceramic product was developed based on alumina and alumino-silicate body compositions using napthlene as pore former. The major disadvantages of the hitherto known prior art as referred above are: 1 Use of organic binder makes the process costlier. 2. Some of the organic binders causes pollution on burn out. 3. Process of foaming is costly and not viable for large scale production. in a co-pending patent application no. NF-11 / 03, we have described and claimed a process a process for the production of low cost porous ceramic tiles using marble dust. This process comprises of calcining marble dust, mixing intimately 15 to 48 wt% of the said clacined marble dust, 52 to 64 wt% of clay and 0-33 wt% wollastonite, to obtain a mixture, slaking the said mixture with water, air drying the slaked batch for a period of 40 to 48 hrs, shaping the product by known method, subjecting the shaped dried product so obtained to hydrothermal treatment in a an autoclave under a saturated vapor pressure may be in the range of 100 to 160 psi for a period in the range of 0 to 2 hours. In this process calcined marble dust is used and solidification of products is done by hydrothermal treatment. The main object of the present invention is to provide a process for the production of high strength porous ceramic tiles utilizing solid industrial wastes, which obviates the drawbacks of the hitherto known prior art, as mentioned above. Another object of the present invention is to utilize industrial wastes, particularly marble dust and fly ash, which create enormous environmental pollution and health hazards. Yet another object of the present inver' " is to utilize marble dust in its as received form without calcinations. Still another object of the present invention is to provide a process for the production of lighter and high strength building materials. Still yet another object of the present invention is to produce a product which is machinable and can be converted to required shapes and sizes by cutting. In the present invention there is provided a process for the production of low cost porous ceramic tiles using waste materials like marble dust and fly ash, in combination with or without clay, by firing at temperatures below 1200°C. Marble dust fines, a waste material, generated by the marble industries during cutting and polishing processes is used as a starting material. Another dreaded waste material, fly ash, mainly generated by the thermal power plant boilers, is also utilized. Formation of low temperature glassy phase on reaction between the constituent materials during firing is responsible for the strength development. The product produced by the present invention possesses bulk density in the range of 1.26 to 1.52 gm/cc, apparent porosity in the range of 36.5 to 47.5% and cold crushing strength in the range of 122 to 353 kg/cm2. Accordingly, the present invention provides a for the production of high strength porous ceramic tiles utilizing industrial solid wastes, which comprises: (a) mixing intimately 50 to 80 wt% marble dust waste having major chemical constituents such as 35 to 37 wt% CaO, 2 to 3 wt% N2O + K20, 5 to 8 wt% MgO, 0 to 25 wt% Si02, 2 to 4 wt% Al203 and has 20 to 22 wt% loss on ignition with an average particle size (d50) in the range of 25 to 28 micrometer, with 20 to 40 wt% fly ash having chemical constituents such as 58 to 60 wt% SiO2, 27 to 30 wt% Al2O3, 2 to 4 wt% Fe2O3, 2 to 3 wt% TiO2, 2 to 3 wt% CaO, 1 to 2 wt% Na2O+K2O and has 1 to 2 wt% loss on ignition with an average particle size (d50) in range of 14 to 16 micro meter, and 0 to 12 wt% clay powder such as kaolin or ball clay type to obtain batch, (b) mixing the above said batch as obtained from step (a) with green binder solution selected from the group consisting of polyvinyl alcohol, dextrin, carboxy methyl cellulose to obtain a product, (c) shaping the above said products as obtained from step (b) by subjecting to hydraulic compaction at a pressure in the range of 350 to 400 kg/cm2 to obtain shaped product, (d) Drying the above said shaped products as obtained from step (c) at a temperature ranging from 110 to 120°C for a period ranging from 24 to 30 hours to obtain dry product, (e) firing the above said dried product as obtained form step (d) at a temperature ranging from 1150 to 1200°C followed by soaking for a period ranging from 1 to 2 hours to obtain high strength porous ceramic tiles . In another embodiment of the present invention, the clay powder is such as kaolin or ball clay type and passes through 200 mesh BS sieve (75 micro meter). In yet another embodiment of the present invention, the dry mixing time of the batch is in the range of 25 to 30 minutes. In still yet another embodiment of the present invention, the quantum oft green binder solution is in the range of 5 to 6 wt% of total body mix. In a yet further embodiment of the present invention, the mixing of the green binder solution with the batch is for a time period in the range of 15 to 20 minutes. In the present invention marble dust is used as a major waste material, which contains calcite (CaCO3) as major phase and wollastonite (CaO, SiO2), diopside (Ca, Mg) Si03], aragonite (CaC03) as minor phases as detected in XRD studies. Fly ash. which is another major waste material used in the process, contains Quartz (SiO?), muilite (3 AbCK 2SiO?) or siilimanite (AI2O3. 3iO?). These two ,/aste materials in combination with or without clay (AI2O3. 2SiO? 2H20) generate pores on heating at a temperature in the range of 900 to iOOO°C due to decomposition of carbonates. Beyond this temperature, a reaction sintering between lime and aiummo-siiicate results in formation of low temperature liquid phases anorthite (CaO AI2O3. 2SiO2) or gehlenite ( 2 CaO AI2O3. SiO2) phases, which binds the particles together and develops strength. Presence of free quartz and other impurities from both marble dust and fly ash might have reduced the iiquidus temperature further in association with anorthite resulting porous (lighter) products with sufficient strength in the sintering range of 1150 to 1200°C. Presence of muilite in fly ash also contributes towards strength development. The novelty of the present invention resides in providing high strength porous ceramic tiies by reaction sintering of industrial solid wastes namely marble dust and fly ash with or without clay in the temperature range of 1150 to 1200°C. Insitu pore formation during decomposition of calcite (CaCO3) mineral present in marble dust in the temperature range of 900 to 1000°C and binding of particles by low temperature ceramic bond (gehlenite / anorthite) formed in the temperature range of 1150 to 1200°C are responsible for sintered (bulk density 1.26 to 1.59 gm/cc) porous (apparent porosity 36.5 to 47%) and high strength (cold crushing strength 122 to 352 Kg/cm2) products. The non-obvious inventive steps of the process of the present invention resides in providing a synergistic composition consisting of marble dust and fly ash wastes with or without clay to obtain a mixture. Further the mixture in the form of shaped products on heat treatment at a temperature in the range of 1150 to 1200°C, produces a porous matrix embedded with low temperature glassy phase and this results in high porosity and strength in the product. The detailed process steps of the present invention are as follows: 1. Dry mixing intimately 50 to 80 wt% marble dust, 20 to 40 wt% fly ash, 0 to 12 wt% clay powder for a period of 25 to 30 minutes. 2. Thorough mixing of the batch with green binder solution for a period of 15- 20 minutes. 3. Shaping of articles by hydraulic compaction at a specific pressure of 350 to 400 kg/cm2. 4. Drying of shaped articles in the temperature range of 110-120°C for a period of 24 to 30 hrs in an electric oven. 5. Firing of dried articles in the temperature range of 1150 to 1200°C for a soaking period of 1 to 2 hours in an electric furnace. The following examples are given by way of illustration of the process of present invention in actual practice. However, the examples, should not be construed to limit the scope of the present invention. Example 1 720 gms of marble dust and 280 gms of fly ash were taken and dry mixed for 25 mins. Next 60 cc of PVA solution was added to the mixed body and further mixing was done for 15 mins. The mixture was then shaped to tiles at a compaction pressure of 350 kg/cm2. Pressed products were then dried at 110°C for 30 hrs and fired at 1150°C for a soaking period of 1 hr. Sintered products showed a bulk density of 1.26 gm/cc, apparent porosity of 46.93% and cold crushing strength of 135 kg/cm2. Example 2 640 gms of marble dust. 310 gms of fly ash and 50 gms of clay were taken and dry mixed for 25 mins. Next 55 cc of PVA solution was added to the mixed body and further mixing was done for 15 mins. The mixture was then shaped to tiles at a compaction pressure of 400 kg/cm2. Pressed products were then dried at 120°C for 30 hrs and fired at 1200°C for a soaking period of 1 hr. Sintered products showed a bulk density of 1.42 gm/cc, apparent porosity of 41.1% and cold crushing strength of 225 kg/cm2. Example 3 800 gms of marble dust and 200 gms of fly ash were taken and dry mixed for 30 mins. Next 60 cc of PVA solution was added to the mixed body and further mixing was done for 20 mins. The mixture was then shaped to tiles at a compaction pressure of 350 kg/cm2. Pressed products were then dried at 110°C for 24 hrs and fired at 1150°C for a soaking period of 2 hr. Sintered products showed a bulk density of 1.27 gm/cc, apparent porosity of 47.5% and cold crushing strength of 122 kg/cm2. Example 4 570 gms of marble dust, 400 gms of fly ash and 30 gms of clay were taken and dry mixed for 25 mins. Next 50 cc of PVA solution was added to the mixed body and further mixing was done for 15 mins. The mixture was then shaped to tiles at a compaction pressure of 350 kg/cm2. Pressed products were then dried at 110°C for 30 hrs and fired at 1200°C for a soaking period of 1 hr. Sintered products showed a bulk density of 1.5 gm/cc, apparent porosity of 37.19% and cold crushing strength of 345 kg/cm2. Example 5 500 gms of marble dust, 380 gms of fly ash and 120 gms of clay were taken and dry mixed for 30 mms. Next 50 cc of PVA solution was added to the mixed body and further mixing was done for 20 mins. The mixture was then shaped to tiles at a compaction pressure of 400 kg/cm2. Pressed products were then dried at 120°C for 30 hrs and fired at 1200°C for a soaking period of 1 hr. Sintered products showed a bulk density of 1.52 gm/cc, apparent porosity of 36.5% and cold crushing strength of 352 kg/cm2. The main advantages of the process of the present invention are: 1. The present process utilizes more waste materials in larger quantities thus helping to minimize the environmental pollution. 2. The present process does not use any extra pore forming material to generate porosity in the products. 3. The products developed by the present process are much lighter, hence suitable for building construction work. 4. The products developed by the present process is machinable, thus can be made into any desired shapes & sizes by cutting. 5. The tailor-made properties of the product produced by the present process are achievable. 6. The present process minimizes the extra manufacturing step of marble dust calcinations. Marble dust is used in the raw form in the batch which generates porosity or heat treatment, thus making the process simple. We claim: 1. A process for the production of high strength porous ceramic tiles utilizing industrial solid wastes, which comprises: (a) mixing intimately 50 to 80 wt% marble dust waste having major chemical constituents such as 35 to 37 wt% CaO, 2 to 3 wt% N2O + K2O, 5 to 8 wt% MgO, 0 to 25 wt% SiO2, 2 to 4 wt% Al2O3 and has 20 to 22 wt% loss on ignition with an average particle size (d50) in the range of 25 to 28 micrometer, with 20 to 40 wt% fly ash having chemical constituents such as 58 to 60 wt% Si02, 27 to 30 wt% Al2O3, 2 to 4 wt% Fe2O3, 2 to 3 wt% Ti02, 2 to 3 wt% CaO, 1 to 2 wt% Na2O+K2O and has 1 to 2 wt% loss on ignition with an average particle size (d50) in range of 14 to 16 micro meter, and 0 to 12 wt% clay powder such as kaolin or ball clay type to obtain batch, (b) mixing the above said batch as obtained from step (a) with green binder solution selected from the group consisting of polyvinyl alcohol, dextrin, carboxy methyl cellulose to obtain a product, (c) shaping the above said products as obtained from step (b) by subjecting to hydraulic compaction at a pressure in the range of 350 to 400 kg/cm2 to obtain shaped product, (d) Drying the above said shaped products as obtained from step (c) at a temperature ranging from 110 to 120°C for a period ranging from 24 to 30 hours to obtain dry product, (e) firing the above said dried product as obtained form step (d) at a temperature ranging from 1150 to 1200°C followed by soaking for a period ranging from 1 to 2 hours to obtain high strength porous ceramic tiles . 2. A process as claimed in claim 1 wherein the clay powder passes through 200 mesh BS sieve (75 micro meter). 3. A process as claimed in claim 1, wherein the dry mixing time of the batch is in the range of 25 to 30 minutes. 4. A process as claimed in claim 1, wherein the quantum oft green binder solution is in the range of 5 to 6 wt% of total body mix. 5. A process as claimed in claim 1, wherein the mixing of the green binder solution with the batch is for a time period in the range of 15 to 20 minutes. 6. A process for the production of high strength porous ceramic tiles utilizing industrial solid wastes, substantially as herein described with reference to the examples.

Documents:

515-DEL-2003-Abstract-(23-12-2008).pdf

515-del-2003-abstract.pdf

515-DEL-2003-Claims-(23-12-2008).pdf

515-del-2003-claims.pdf

515-DEL-2003-Correspondence-Others-(23-12-2008).pdf

515-del-2003-correspondence-others.pdf

515-del-2003-correspondence-po.pdf

515-DEL-2003-Description (Complete)-(23-12-2008).pdf

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

515-del-2003-form-1.pdf

515-del-2003-form-18.pdf

515-DEL-2003-Form-2-(23-12-2008).pdf

515-del-2003-form-2.pdf

515-DEL-2003-Form-3-(23-12-2008).pdf

515-del-2003-form-3.pdf