A RUDIMENTARY TREATISE ON THE MANUFACTURE OF BRICKS AND TILES
1 GENERAL INFORMATION ON CERAMIC MANUFACTURING 1 11 Historical origins 1 12 Characteristics of ceramics 1 13 Geographical distribution and general economic considerations 3 14 Key environmental issues 4 15 Ceramics sectors 5 151 Bricks and roof tiles 6 152 Vitrified clay pipes 7 153 Refractory products 8 154 Expanded clay aggregates 9 155 Wall and floor tiles 9 156 Table- and ornamentalware (household ceramics) 11 157 Sanitaryware 11 158 Technical ceramics 12 159 Inorganic bonded abrasives 12 2 APPLIED PROCESSES AND TECHNIQUES IN CERAMIC MANUFACTURING 13 21 Raw materials 13 22 General production process description 14 221 Storage and transport of raw materials 15 222 Preparation of raw materials 15 2221 Pre-drying 15 2222 Pre-blending 15 2223 Weathering/souring 15 2224 Primary and secondary crushing, grinding and screening 16 2225 Dry or wet milling (grinding) 16 2226 Dry screening/air classification 16 2227 Spray drying 17 2228 Calcining 17 2229 Synthetic base materials 17 22210 Frits and glazes, glaze preparation 17 223 Component mixing 18 2231 General 18 2232 Continuous mixers 18 2233 Batch mixers 18 224 Shaping/forming of ware 19 2241 General 19 2242 Pressing 19 22421 Mechanical pressing 19 22422 Hydraulic pressing 19 22423 Impact pressing 19 22424 Friction pressing 19 22425 Isostatic pressing 20 2243 Extrusion 20 2244 Moulding 20 2245 Slip casting 20 2246 Fusion casting 21 225 Drying of ceramic products 21 2251 General 21 2252 Hot floor dryers 21 2253 Chamber dryers (intermittent) 21 2254 Tunnel dryers (continuous) 22 2255 Vertical ‘basket’ dryers 22 2256 Horizontal multi-deck roller dryers 22 CONTENTS 2257 Dehumidifying dryers 22 2258 Infrared and microwave dryers 23 226 Surface treatment and decoration of ceramic products23 2261 Texturing of clay products23 2262 Applied facings23 2263 Glazing, engobing and other decorating techniques 23 227 Firing 24 2271 Aims of firing 24 2272 Physico-chemical changes during firing24 2273 Intermittent (periodic) kilns 25 2274 Continuous kilns 26 22741 Chamber (Hoffmann) kilns 26 22742 Tunnel kilns 26 22743 Roller hearth kilns27 22744 Sliding bat kilns 28 2275 Clamp firing28 2276 Rotary kilns28 2277 Fluidised beds 29 2278 Cooling stage heat recovery29 228 Subsequent treatment (product finishing)29 2281 Machining (grinding, drilling, sawing) 29 22811 Wet grinding 29 22812 Dry grinding29 22813 Drilling29 22814 Sawing 30 2282 Polishing 30 2283 Carbon enrichment (refractory products)30 2284 Tumbling of facing bricks 30 229 Addition of auxiliary materials31 2291 Jointing materials (pipes)31 2292 Silicones/water repellents 31 2293 Insulation materials31 2294 Carding and plating (refractory bricks)31 2295 Adhesives31 2296 Final assembly 31 2210 Sorting, packaging and storage31 2211 Supply and disposal (off-gas treatment and process waste water treatment) facilities 32 2212 Recycling in the ceramic industry 32 2213 General process flow diagram showing different processing paths33 23 Description of techniques for the manufacture of ceramic products sector by sector34 231 Bricks and roof tiles34 2311 Raw materials 35 2312 Preparation of raw materials 39 2313 Shaping 40 2314 Drying, glazing and engobing41 2315 Firing 41 2316 Subsequent treatment43 2317 Input and output flows in the manufacture of bricks and roof tiles 43 232 Vitrified clay pipes 44 2321 Raw materials 45 2322 Preparation of raw materials 47 2323 Shaping 47 2324 Drying and glazing 47 2325 Firing 47 2326 Subsequent treatment48 2327 Input and output flows in the manufacture of vitrified clay pipes 48 233 Refractory products 49 2331 Raw materials 50 2332 Preparation of raw materials 51 2333 Shaping 51 2334 Drying52 2335 Firing 52 2336 Subsequent treatment53 2337 Special procedures 53 2338 Input and output flows in the manufacture of refractory products 54 234 Expanded clay aggregates 54 2341 Raw materials, additives and auxiliary agents 56 2342 General system and process technology 57 23421 Shaping 57 23422 Thermal process technology 57 23423 Chemical reaction during expansion 58 23424 Subsequent sieving and crushing 58 2343 Input and output flows in the manufacture of expanded clay aggregates 58 235 Wall and floor tiles 59 2351 Raw materials 60 2352 Preparation of raw materials 61 2353 Shaping 61 2354 Drying 62 2355 Firing and glazing 62 2356 Subsequent treatment 63 2357 Input and output flows in the manufacture of wall and floor tiles 63 236 Table- and ornamentalware (household ceramics) 64 2361 Raw materials 65 2362 Preparation of raw materials 65 2363 Shaping 66 2364 Drying 67 2365 Firing, glazing and decoration 67 2366 Subsequent treatment 70 2367 Input and output flows in the manufacture of household ceramics 70 237 Sanitaryware 71 2371 Raw materials 71 2372 Preparation of raw materials 72 2373 Shaping 72 2374 Drying and glazing 72 2375 Firing 73 2376 Subsequent treatment 74 2377 Input and output flows in the manufacture of sanitaryware 74 238 Technical ceramics 75 2381 Raw materials 77 2382 Preparation of raw materials 78 2383 Shaping 79 2384 Machining 80 2385 Glazing, engobing and metallisation 81 2386 Drying, burning out and pre-firing 82 2387 Firing/sintering 83 2388 Subsequent treatment 84 2389 Input and output flows in the manufacture of technical ceramics 84 239 Inorganic bonded abrasives 85 2391 Raw materials 85 2392 Preparation of raw materials 85 2393 Shaping 86 2394 Drying 86 2395 Firing 86 2396 Subsequent treatment 86 2397 Input and output flows in the manufacture of inorganic bonded abrasives 86 3 CURRENT EMISSION AND CONSUMPTION LEVELS 89 31 Emissions – general considerations 89 311 Emissions to air 89 3111 Dust (particulate matter) 89 3112 Gaseous emissions 89 31121 Sulphur dioxide and other sulphur compounds 89 31122 Oxides of nitrogen and other nitrogen compounds 89 31123 Carbon monoxide (and carbon dioxide) 90 31124 Volatile organic compounds (VOCs) 90 31125 Metals and their compounds 90 31126 Chlorine and its compounds90 31127 Fluorine and its compounds 91 312 Emissions to water91 313 Process losses/waste 92 314 Emissions of noise92 315 Possible emission sources and emission paths 93 32 Consumption – general considerations 94 321 Energy consumption94 322 Water consumption94 323 Raw materials consumption94 33 Presentation of emission and consumption data 95 331 Bricks and roof tiles95 3311 Emission data95 3312 Consumption data 104 332 Vitrified clay pipes 106 3321 Emission data106 3322 Consumption data 108 333 Refractory products 109 3331 Emission data109 3332 Consumption data 111 334 Expanded clay aggregates 113 3341 Emission data113 3342 Consumption data 115 335 Wall and floor tiles 116 3351 Emission data116 3352 Consumption data 120 336 Table- and ornamentalware (household ceramics) 121 3361 Emission data121 3362 Consumption data 125 337 Sanitaryware 126 3371 Emission data126 3372 Consumption data 129 338 Technical ceramics 130 3381 Emission data130 3382 Consumption data 133 339 Inorganic bonded abrasives 134 3391 Emission data134 3392 Consumption data 136 4 TECHNIQUES TO CONSIDER IN THE DETERMINATION OF BAT FOR CERAMIC MANUFACTURING137 41 Reduction of energy consumption (energy efficiency) 138 411 Improved design of kilns and dryers 138 412 Recovery of excess heat from kilns 140 413 Cogeneration/combined heat and power plants 141 414 Substitution of heavy fuel oil and solid fuels by low emission fuels143 415 Modification of ceramic bodies 144 42 Emissions of dust (particulate matter) 146 421 Measures for dusty operations 146 422 Measures for bulk storage areas 147 423 Separation/filter systems148 4231 Centrifugal separators148 4232 Bag filters 148 4233 Sintered lamellar filters151 4234 Wet dust separators152 4235 Electrostatic precipitators (ESP)153 43 Gaseous compounds 155 431 Reducing the input of pollutant precursors155 432 Addition of calcium rich additives 157 433 Process optimisation159 4331 Optimising the heating curve159 4332 Reduction of water vapour levels in the kiln gases160 4333 Internal carbonisation gas combustion161 4334 Low-NOX burners 162 434 Sorption plants (adsorbers, absorbers) 163 4341 Cascade-type packed bed adsorbers 163 4342 Module adsorber systems 167 4343 Dry flue-gas cleaning with a filter (bag filter or electrostatic precipitator) 168 4344 Wet flue-gas cleaning 171 4345 Activated carbon filters 173 4346 Biological scrubbers 173 435 Afterburning 174 4351 Thermal afterburning 174 4352 Catalytic afterburning 176 436 Examples of operational data, efficiencies, consumption and cost data for different fluegas cleaning techniques 178 44 Process waste water 182 441 Water used as a raw material 182 442 Water used as a heat exchange vehicle 182 443 Water used as a scrubbing agent 182 444 Water used as a cleaning agent 182 445 Objectives and solutions for the reduction of process waste water (emissions and consumption) 182 4451 Process optimisation 183 4452 Systems of process waste water treatment 184 45 Process losses/waste