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pulp used in asbestos indutries

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  1. 1. 1.Based on PulpingProcess 3. Based on Bleaching Fully Mechanical 2. Based on Raw Material (GW, PGW, RMP) Totally Chlorine Mechanical & Wood (HW, SW) Free (TCF) Thermal (TMP) Agricultural Residue Elemental Chlorine Semi-mechanical, (Straws) Free (ECF) semi-chemical Annual Plants & Grasses Chlorine Bleaching (CTMP) (Hemp, Jute, Kenaf, (Chlorine gas & Semi chemical Bamboo) Hypochlorite) (NSSC, Cold Soda) Rags Oxygen/Ozone Fully Chemical Recycled or secondary Fiber Bleached. (Sulfite, sulfate) Deinked Unbleached Soft Cook Fully Chemical (Rayon, viscose)4. Based on Yield 5. Based on Fiber Length Very High Yield (>95%) - GW, PGW High Yield (85-95%) - RMP, TMP Long Fiber Pulp (>10mm) - Cotton, Medium High Yield (65-85%) - Hemp, Flax, Jute CTMP, NSSC, CMP Medium Fiber Pulp (2 - 10mm) - Medium Yield (45-65%) - (Sulfite, Northern S/W, H/W Sulfate) Short Fiber Pulp (< 2mm) - Tropical Medium Low Yield (35-45%) Straw, H/W, straws, grasses Grass, Bagasse chemical pulp Low Yield (<35%) - Rayon, viscoseThe three most important Parameters which defines the pulp are. 1.) Fiber Length, 2.)Brightness, 3.) Pulping process used. e.gWEHRHAHN plants (equipment)Individually designed to meet your requirements.Wehrhahn supplies plants with capacities from2 - 20 t/h. The fibre cement production process has continuously been further developed to reducematerial and energy consumption figures. Process related cut-off materials and rejectsare immediately recycled in the process. Surplus water runs through a treatment plant andreturns into the production process.
  2. 2. For the production of the large variety of sheets, two technologies have proven to be suitable:Air cured (CC) fibre cement sheets are perfect for roofing products and all applicationswhere the sheets are directly exposed to harsh weather conditions. Autoclaved (CCA)sheets are the choice for façades, cladding and all interior applications.• CC = Cellulose Cement SheetsCC sheets are manufactured from cement and fillers. A blendof virgin cellulose and synthetic fibres such as PVA or PAN areused as fibre reinforcement.• CCA = Cellulose Cement Autoclaved SheetsCCA sheets are manufactured from cement, finely groundsilica sand and some additives.Virgin cellulose is used as fibre reinforcement.Compressed sheetsCC and CCA sheets can be compressed in a single sheet or stack press. Pressing increases the sheet densityand strength. The sheet resistance towards freeze/thaw conditions is enhanced. Pressing provides a very smoothsurface finish.Which technology for which product? CC sheets for CCA sheets for Roofing Lap siding (corrugated or flat) (with timber pattern, wood grain or smooth)
  3. 3. Façades Façades Fencing Fencing - External base for plaster - All internal applicationsPlant capacity range Market Capacities t/hour Number of sheeting machine cylinders Sheeting machine width Small 2-3 2 single widthMedium 8 - 10 4-6 single width Large up to 20 5 double widthNote: Other capacities upon request.WEHRHAHN leading in autoclave technologyWEHRHAHN is the global leader with superior technology to manufacture machines forthe production of autoclaved calcium-silicate products, such as fibre-cement sheets,aerated concrete blocks and panels, insulation boards, etc.Sand grinding, sand slurry dosing as well as autoclaves, automatic pressure control andautomatic condensate discharge are equally vital parts of Wehrhahn‘s know-how.Production of fibre cement sheets in Wehrhahn plantsState-of-the-art highly efficient machines, plants and technologies for the production offibre cement sheetsMaterial PreparationLowest production costs due to highly efficient machines and technologies This includes the material preparation withsand grinding mill, sand slurry silos as well as openers and refiners for cellulose.Dosing and mixing / sheet production
  4. 4. Wehrhahns computerized smart dosing and mixing plant "WECOMIX" prepares a slurry which is further dilutedand fed into the sieve cylinder sheeting machine. Thin layers are formed on 3 to 6 sieve cylinders and transferredonto a felt. The layers are accumulated around the forming roller until the preset thickness has been reached andthe sheet can automatically be cut off.Thickness controlWehrhahns advanced self-adjusting sheet thickness control system ensures minimum thickness variations. Thissaves material (no overthickness) and reduces rejects (underthickness) which finally increases plant output andeconomy for Wehrhahn customers.CuttingWehrhahn supplies the full range of downstream machines including cutters for all purposes such as cutting andpunching press, guillotine knife cutter, water jet cutter or just circular knife cutter.PressingWehrhahns single sheet presses for corrugated or embossed roofing sheets or stack presses for highcompressed flat sheets improve the sheet density and quality - an important factor for improved frost resistance.Autoclaving / calcium-silicateWehrhahn provides all equipment and extensive know-how for the steam curing technology as this is alsoprocess-relevant for Wehrhahns AAC (autoclaved aerated concrete) block and panel plants. Wehrhahnsautomatic autoclave system (WACO) allows easy control of the complex chemical process in the autoclave.Coloured sheetsIf your market requires more beautiful roofing, Wehrhahn also provides a range of equipment for colouringsheets, such as through-pigmented, top layer, pigmented or surface paint-coated. Paint coating increases beautyand improves quality.
  5. 5. > Production > Plants (equipment) > ProductsStartpage > Fibre Cement > Products
  6. 6. Fibre cement sheets for façade, roof and internal applicationA unique and versatile building materialFew building materials offer a combination of architectural scope and strong technical specification as convincingas fibre cement cladding and roofing.
  7. 7. Fibre cement combines strength with ease of handling and stylish versatile colour options.Fibre cement gains its impressive strength in a special manufacturing process where thin layers of fibre cementare laminated and compressed under high pressure followed by air curing or autoclave curing.A major advantage of fibre cement is its ability to resist all kinds of weather conditions. Frost and thaw, heat, haleor rain do not pose a threat to fibre cement. Inside buildings fibre cement is applied as backer board in wet areasor for dry walls in heavy duty applications where fire resistance and strength are the dominant requirements.Architects love fibre cement, elegantly finished with a wide range of colours to select from. Sheets are easy toinstall and can be cut to any required dimensions or edge details.Fibre cement sheets are used for residential, industrial and agricultural applications. Its appearance andadvantageous characteristics make it the ideal material for the following applications:External cladding / caçades / fencingFlat sheets in various sizes and colours (coated, pigmented or painted), as lap siding or planks, preferably withtimber pattern have conquered many markets.Applications:• façades• cladding / siding• ridges, eaves and soffits• fencing• base for plaster / stuccoFaçadesFaçade sheets are a durable alternative to stucco and• can be applied even during heavy frost when stucco cannot be applied• can cover and protect exterior wall insulation• are used for exterior wall cladding of cottages and townhouses, beautiful (naturally looking) woodgrain planks (sidings) and provide architectural beautyFor the surface treatment of fibre cement, many options and colours are applicable.
  8. 8. Internal claddingFlat sheets which offer unsurpassed properties in fire resistance, dimensional stability, water resistance andacoustical properties can be used in a wide variety of different applications.Applications:• internal lining in wet areas• perfect base for ceramic wall tiles (backer boards)• partitions• fire resistance application in hospitals or kindergarden• floors and ceilingsFibre cement allows water diffusion in both directions. Water can be absorbed and easily be released. Thisresults in convenient climatic conditions inside buildings.Roofing, corrugated roofing and façadesFibre cement has been used as a roofing material for decades. Here small sized shingles / slates and corrugatedsheets have proven to be the best choice. Different sizes and colours to meet the many individual requirementscan be found in the market.Products:• shingles / slates, mostly highly compressed and painted, stand for architectural beauty• corrugated sheets, painted in numerous colours, may be used for external cladding or fencingapplications
  9. 9. Asbestos RoofingThe last 20 years has seen growing concerns over asbestos and many propertyowners are faced with the dilemma of what to do once their old roof starts todeteriorate and leak. Many roofs have been removed in the past and replaced due tohealth concerns whilst others have been replaced with better insulated roofingmaterials.What is Asbestos Cement?Asbestos cement is a mixture of cement and asbestos (usually about 10-15% of thetotal product) forming a hard material often used as corrugated roofing on sheds,garages, farm buildings and industrial units. Asbestos cement usually containedwhite asbestos (chrysotile) but older types may contain blue (crocidolite) or brown(amosite).
  10. 10. The type used is not really important as all asbestos is hazardous, althoughasbestos cement does not release many fibres and is relatively low risk. It issometimes difficult to tell the difference between an asbestos cement product and alow-density insulation board. Where the product has been used as a roofing orcladding product open to the weather, you can be confident that the product isasbestos cement.Safety firstIf your roof is made with Asbestos Cement, a licence is not needed to remove it.However, in compliance with HSE, All Roofing and Building is highly experienced inhandling the product and fully aware of the strict guidelines that must be followed toremove and dispose of the product correctly. A licensed contractor is only needed towork on High Risk Asbestos such as pipe insulation or insulation panels – NOT onAsbestos cement which is considered much less dangerous.It is still important to take precautions with handling old asbestos sheets andprotective overalls and face masks are recommended. Cutting is consideredhazardous and therefore not recommended.Whilst the HSE do recognise the hazard of Asbestos in fibre cement sheets, it is farmore likely that serious dangers come from walking on the roofs without protectionfrom falling through them.Many serious accidents in the past have arisen through people falling through themas the asbestos sheet can break under the persons feet. With Health & safety nowbeing a formidable force any activity on a asbestos roof should be done only aftersafety netting has been erected. So even if you have roof-lights to be changed orminor repairs are needed this is essential before any work or inspection is carriedout.Should all asbestos sheets be dumped?With so many agricultural buildings in use there has to be a call for using the roofingsheets again as many are perfectly good when stripping off roofs.The main problem with re-using old asbestos sheets is that they get slippery whenthey are wet, dry conditions would be needed to refix them but then again any workon old roofs should be done in good conditions. However in a world that considersrecycling as a good thing it has to be right that this should be done wheneverpossible. Other benefits are that it stops old buildings that have had repairs fromlooking like patchwork quilts, due to the use of new sheets.Occassionally we have in stock used fibre cement sheets which we use for repairs,these sometimes come in when newish farm buildings are changed to be used forindustrial.How experienced are we at strip and re-sheeting asbestos roofing?
  11. 11. Well, we have stripped literally 1000′s of tons off and our biggest job to date was a10,000 sq meter double skin off with a double skin tin replacement. We are alwaysinterested in anything bigger or smaller re-sheeting jobs than that..