Reference Document on Best Available Techniques in the

2,71
MB Ceramic Manufacturing Industry

260
stron

6054
ID JRC-IPTS Instituto de Prospectiva Tecnológica (IPTS)

2007
rok

EXECUTIVE SUMMARYI

PREFACEXI

SCOPE XXV

1 GENERAL INFORMATION ON CERAMIC MANUFACTURING 1

1.1 Historical origins 1

1.2 Characteristics of ceramics. 1

1.3 Geographical distribution and general economic considerations . 3

1.4 Key environmental issues. 4

1.5 Ceramics sectors 5

1.5.1 Bricks and roof tiles . 6

1.5.2 Vitrified clay pipes. 7

1.5.3 Refractory products 8

1.5.4 Expanded clay aggregates 9

1.5.5 Wall and floor tiles. 9

1.5.6 Table- and ornamentalware (household ceramics). 11

1.5.7 Sanitaryware 11

1.5.8 Technical ceramics. 12

1.5.9 Inorganic bonded abrasives 12

2 APPLIED PROCESSES AND TECHNIQUES IN CERAMIC MANUFACTURING . 13

2.1 Raw materials 13

2.2 General production process description . 14

2.2.1 Storage and transport of raw materials. 15

2.2.2 Preparation of raw materials 15

2.2.2.1 Pre-drying. 15

2.2.2.2 Pre-blending . 15

2.2.2.3 Weathering/souring 15

2.2.2.4 Primary and secondary crushing, grinding and screening 16

2.2.2.5 Dry or wet milling (grinding). 16

2.2.2.6 Dry screening/air classification 16

2.2.2.7 Spray drying. 17

2.2.2.8 Calcining 17

2.2.2.9 Synthetic base materials . 17

2.2.2.10 Frits and glazes, glaze preparation . 17

2.2.3 Component mixing. 18

2.2.3.1 General . 18

2.2.3.2 Continuous mixers . 18

2.2.3.3 Batch mixers 18

2.2.4 Shaping/forming of ware . 19

2.2.4.1 General . 19

2.2.4.2 Pressing 19

2.2.4.2.1 Mechanical pressing. 19

2.2.4.2.2 Hydraulic pressing 19

2.2.4.2.3 Impact pressing 19

2.2.4.2.4 Friction pressing. 19

2.2.4.2.5 Isostatic pressing 20

2.2.4.3 Extrusion 20

2.2.4.4 Moulding 20

2.2.4.5 Slip casting. 20

2.2.4.6 Fusion casting 21

2.2.5 Drying of ceramic products 21

2.2.5.1 General . 21

2.2.5.2 Hot floor dryers 21

2.2.5.3 Chamber dryers (intermittent) 21

2.2.5.4 Tunnel dryers (continuous) 22

2.2.5.5 Vertical ‘basket’ dryers 22

2.2.5.6 Horizontal multi-deck roller dryers 22

xvi Ceramic Manufacturing Industry

2.2.5.7 Dehumidifying dryers.22

2.2.5.8 Infrared and microwave dryers .23

2.2.6 Surface treatment and decoration of ceramic products.23

2.2.6.1 Texturing of clay products23

2.2.6.2 Applied facings.23

2.2.6.3 Glazing, engobing and other decorating techniques .23

2.2.7 Firing 24

2.2.7.1 Aims of firing .24

2.2.7.2 Physico-chemical changes during firing.24

2.2.7.3 Intermittent (periodic) kilns 25

2.2.7.4 Continuous kilns .26

2.2.7.4.1 Chamber (Hoffmann) kilns .26

2.2.7.4.2 Tunnel kilns 26

2.2.7.4.3 Roller hearth kilns.27

2.2.7.4.4 Sliding bat kilns 28

2.2.7.5 Clamp firing28

2.2.7.6 Rotary kilns.28

2.2.7.7 Fluidised beds .29

2.2.7.8 Cooling stage heat recovery29

2.2.8 Subsequent treatment (product finishing).29

2.2.8.1 Machining (grinding, drilling, sawing).29

2.2.8.1.1 Wet grinding .29

2.2.8.1.2 Dry grinding29

2.2.8.1.3 Drilling29

2.2.8.1.4 Sawing 30

2.2.8.2 Polishing .30

2.2.8.3 Carbon enrichment (refractory products)30

2.2.8.4 Tumbling of facing bricks 30

2.2.9 Addition of auxiliary materials.31

2.2.9.1 Jointing materials (pipes)31

2.2.9.2 Silicones/water repellents .31

2.2.9.3 Insulation materials.31

2.2.9.4 Carding and plating (refractory bricks).31

2.2.9.5 Adhesives31

2.2.9.6 Final assembly 31

2.2.10 Sorting, packaging and storage.31

2.2.11 Supply and disposal (off-gas treatment and process waste water treatment) facilities .32

2.2.12 Recycling in the ceramic industry 32

2.2.13 General process flow diagram showing different processing paths33

2.3 Description of techniques for the manufacture of ceramic products sector by sector.34

2.3.1 Bricks and roof tiles34

2.3.1.1 Raw materials .35

2.3.1.2 Preparation of raw materials .39

2.3.1.3 Shaping .40

2.3.1.4 Drying, glazing and engobing.41

2.3.1.5 Firing 41

2.3.1.6 Subsequent treatment43

2.3.1.7 Input and output flows in the manufacture of bricks and roof tiles 43

2.3.2 Vitrified clay pipes .44

2.3.2.1 Raw materials .45

2.3.2.2 Preparation of raw materials .47

2.3.2.3 Shaping .47

2.3.2.4 Drying and glazing .47

2.3.2.5 Firing 47

2.3.2.6 Subsequent treatment48

2.3.2.7 Input and output flows in the manufacture of vitrified clay pipes 48

2.3.3 Refractory products 49

2.3.3.1 Raw materials .50

2.3.3.2 Preparation of raw materials .51

2.3.3.3 Shaping .51

2.3.3.4 Drying.52

2.3.3.5 Firing 52

2.3.3.6 Subsequent treatment53

2.3.3.7 Special procedures . 53

2.3.3.8 Input and output flows in the manufacture of refractory products . 54

2.3.4 Expanded clay aggregates 54

2.3.4.1 Raw materials, additives and auxiliary agents . 56

2.3.4.2 General system and process technology. 57

2.3.4.2.1 Shaping. 57

2.3.4.2.2 Thermal process technology. 57

2.3.4.2.3 Chemical reaction during expansion 58

2.3.4.2.4 Subsequent sieving and crushing 58

2.3.4.3 Input and output flows in the manufacture of expanded clay aggregates. 58

2.3.5 Wall and floor tiles. 59

2.3.5.1 Raw materials. 60

2.3.5.2 Preparation of raw materials 61

2.3.5.3 Shaping. 61

2.3.5.4 Drying 62

2.3.5.5 Firing and glazing 62

2.3.5.6 Subsequent treatment . 63

2.3.5.7 Input and output flows in the manufacture of wall and floor tiles 63

2.3.6 Table- and ornamentalware (household ceramics). 64

2.3.6.1 Raw materials. 65

2.3.6.2 Preparation of raw materials 65

2.3.6.3 Shaping. 66

2.3.6.4 Drying 67

2.3.6.5 Firing, glazing and decoration 67

2.3.6.6 Subsequent treatment . 70

2.3.6.7 Input and output flows in the manufacture of household ceramics 70