Manufacturing Process for Chrysotile Asbestos Cement Corrugated Sheets

The manufacture of A.C. Sheets is based on the principle of famous “Hatschek” process and is well established in India. In brief the manufacturing process shall involve the following stages: -

Pretreatment of Chrysotile Fibre:

Chrysotile fibre bags of different grades are put in fully enclosed full automatic PLC controlled Bag Opening Device. To minimize the exposure risk of Chrysotile Fibre to the worker, manual handling of Chrysotile Fibre is completely avoided by using a fully enclosed fully automatic PLC Controlled Bag Opening Device with bag shredder through which compressed fibre bags are automatically cut.

Chrysotile fibre passes through the enclosed lump breaker and closely connected screw conveyor to be automatically discharged in the mill and the empty bags are automatically fed in the connected Bag shredder where these are shredded and fed to the Edge runner Mill through a duct 25% to 30% water is added in the mill. The fully automatic Bag opening Device, Lump Breaker, Screw Conveyor, Bag Shredder and mill are completely closed integrated unit. The wet chrysotile fibre along with shredded bag particles are discharged from the mill to a closely connected bucket elevator which discharges the wet chrysotile fibre along with shredded bag articles to a storage in which has a screw conveyor attached at the bottom for discharging the wet chrysotile fibre into a batch weighing Hopper placed on electronic load cells which in turn discharge the pre-determined weighed wet chrysotile fibre into the Hydro-disintegrater where he wet chrysotile fibre is mixed with 2000% of water to form asbestos slurry. The whole system of mill, Bucket, Elevator, Storage Bin, Batch weighing Hopper and Hydro-disintegrater is closely connected and integrated unit as a whole. The automatic Bag Opening Device, Edge runner mill and Cement-fly Ash feeding points are provided with suction hoods. These hoods are connected to a pulse jet bag filter unit through a duct. The entire system is designed keeping in mind zero dust generation and no manual handling of chrysotile fibre is done either dry or wet.

Preparation of slurry:

The treated fibre along with predetermined quantities of fly-ash, cement and pulp are charged into a mixing vessel to form slurry.

Sheet making:

The slurry is then fed into the vat from where layers of slurry are deposited on rotating sieve cylinders inside the vat. This is then transferred to a moving end loss polyester felt which deposits the layer on a rotating drum. The required thickness is achieved by successive transfer of slurry films and the sheets so formed are cut and picked up by the conveyor.

Sheet Moulding:

The sheets from the conveyor are automatically cut at the ends to the desired size and conveyed to the atmospheric corrugators’ machine where the sheets are corrugated and placed in the steel template. The wet edge trimming and cutting including damaged sheets are automatically fed to waste pulped through waste conveyor where the green sheets are re- pulped and returned back to the machine continuously in a closed circuit.

Drying and Curing:

50 corrugated sheets along with templates are loaded on to a trolley and transported to a drying chamber. After drying for 10 – 12 hrs, the sheets are striped from the templates. Thereafter, the sheets are air cured for 28 days.

Source: http://acpma.com/production-process.html

Uses in West not relevant to India

The health issues recorded in the Western countries in the past and which are being highlighted and debated by the anti-asbestos lobbies relate to extensive and uncontrolled usage of the Blue and Brown varieties of Asbestos fibre falling within the amphibole category.

Friable low-density asbestos insulation boards were also used as inner roof to provide better fire protection. These products consisted of asbestos upto 90% in loosely bound form. Such applications exposed workers to uncontrolled inhalation of loose asbestos dust in high concentrations which led to health related problems. Once the ill effects of such applications were documented, such usages were stopped in the western countries decades ago.

Those experiences in the West, do not apply to India, where warm climatic conditions never required such asbestos containing thermal insulation of buildings.

In India, we only use Chrysotile (white) asbestos fibre for the manufacture of asbestos-cement sheets and asbestos-cement pipes which contain a very small quantity of Chrysotile fibre (only 8 –10%). The other raw materials used are cement 45%, fly ash 30 –35% and wood pulp. The asbestos fibres are firmly locked-in or encapsulated within the cement matrix during manufacture so that fibres cannot be emitted into the atmosphere under normal use and thus, poses no health risk to the general public or environment. Several studies abroad have concluded that use of Chrysotile in the manufacture of Asbestos Cement Products under controlled conditions is safe for the workers, environment and the general public.

Source: http://acpma.com/uses-in-west.html

Asbestos & Health

Chrysotile is an inert material and is not toxic to touch, smell or ingestion. Chrysotile fibre can be an occupational health hazard only when its dust is respirable and becomes airborne and when such a dust is inhaled in excessive amounts over a prolonged period. Chrysotile fibre is not a hazard when proper dust control procedures are in operation. Low level exposure to chrysotile, within the limits stipulated by the national and international health authorities poses no measurable risk.

Health risk at a workplace due to inhalation of respirable dust is not unique to chrysotile fibre. Virtually all respirable materials are potential health risks when used in uncontrolled conditions. Chrysotile is only one among such fibres.

In the Western world, during the period of ignorance asbestos fibres of all types including amphibole varieties, in loose form, was extensively sprayed on ceilings and structures to conserve heat. It has been proven by later scientific studies that the health problems that were evidenced in the subsequent decades in the West were due to unregulated and irresponsible usage of asbestos, largely consisting of amphibole varieties. Mining, production and usage of these amphibole varieties of asbestos have subsequently been given up.

In today's well controlled and regulated industrial plants using only Chrysotile type of fibre, occurrence of such diseases do not arise. Nor are any health risks associated with the products containing chrysotile-cement mix, such as corrugated roofing sheets, plain sheets, pressure pipes, etc. etc. as the chrysotile fibre is bonded with cement and cannot escape in to the surrounding environment.

Indian Experience

Permissible Exposure Limit Value (PELV) - As technology has advanced the exposure of workers to Chrysotile fibre in the manufacturing process is kept well below the Permissible Exposure Value (PEV) of 1 f/cc as stipulated by the Ministry of Labour in the Factories Act.

During 2004 & 2005 The Directorate General Factory Advice Service and Labour Institutes (DGFASLI), under the Ministry of Labour, Government of India, undertook studies on "Health Status of Workers in the Asbestos Industry" and "Status of Work Environment in Asbestos Products Manufacturing Industry".

These studies covered 9 factories using Chrysotile fibre in the manufacturing process. A total of 702 workers in the age group of 20 to 50 years were covered. The studies concluded that the workplace emission levels in these industries, were well below the stipulated levels of emission, that is, 1 fibre/cubic centimetre and that no case of asbestosis was detected during the study. (asbestosis is a respiratory disease associated with excess inhalation of asbestos fibre of various types over a prolonged period). Click here for DGFASLI Reports

References:

• Gaensler EA, Asbestos-Related Disorders - Clinical and Epidemiological Aspects, Proceedingsof the Fleischner Society Eighteenth Annual Symposium on Chest Disease. Montreal 1988,17-31.
• Doll R. Mortality from Lung Cancer in Asbestos Workers. British Journalof Industrial Medicine, 1985, 12:81
• Berry G.Newhouse ML.Turok M; combined Effects of Asbestos Exposures and Smoking on Mortality from Lung Cancer in Factory Workers. Lancet 1972, 2:476
• Wagner J.C. et al, British Journal of Industrial Medicine 45: 305-308 (1988).
• Peter Elmes; Mesotheliomas and Chrysotile; The Annals of Occupational Hygiene Vol.38, No.4, August 1994, 547-553
• The National Study on Status of Work Environment in Asbestos Products Manufacturing Industry, 2005.
• The National Study on Status of Workers in the Asbestos Industry, 2004.

Source: http://acpma.com/asbestos-health.html 

Asbestos Cement Products: Truth held hostage – Understanding the facts about White Asbestos

Fact – Dictionary defines fact as verified information about past or present circumstances or events which are presented as objective reality.

In case of present usage of Asbestos, facts are often misrepresented and contorted to present a picture far from reality.   The differentiation of types of asbestos fibers is deliberately ignored by certain anti-asbestos groups.   They omit to mention that White Asbestos, which is only used now, is completely safe under controlled conditions. 

The Asbestos Cement industry has always supported an extensive range of domestic and commercial requirements of the society. Yet the industry has been under constant threat of several myths and negative propaganda. The awareness about asbestos are at a very low level and most people even do not know that there are different types of asbestos and risk potential differs by product and process. It occurs in a number of different forms and the risks posed by them vary considerably... from minimal to severe.

The Asbestos Cement industry, a Rs. 4,500 crore industry, generates employment for about 3 Lakh people in India and contributes over 20 % of the turnover to the government’s exchequer by way of direct and indirect taxes.  Still the usage of asbestos (even white asbestos) has been made by certain groups of vested interests as a contentious issue. It is a misconception that asbestos is hazardous to health, whereas the fact is that today it is not the mixed varieties of asbestos, but it is only Chrysotile (White fibre) variety which is used as approved by national and international scientific authorities and governments. Only safe white fibre is used in India and the unsafe blue and brown fibres are banned. Asbestos Cement products are eco friendly and contain only 8% of white asbestos while the rest consists of Fly ash (30%), cement (40%), water (20%) and pulp (2%). Chrysotile is a natural mineral without any known hazards under controlled usages in Asbestos Cement manufacturing process.

Various organizations are working on a negative propaganda against asbestos and are being funded by multinationals from European Union who want to promote their substitute products in the Indian market. These organizations get active support from steel sheet and pipe manufacturers’ lobby in India which commercially benefits by the increased sale and market share of metal roofing sheets and metal pipes, if manufacture of Asbestos Cement Sheets and Asbestos Cement Pipes is discontinued in India. The campaigns by these organizations are not based on any scientific evidence in India or elsewhere, and are totally dictated by vested commercial interests. The Activists try to create hysteria by quoting data and experience of past Asbestos usage notably in the European Union, which has no relevance at all in Indian usage.

International and national anti-asbestos bodies allege that asbestos is a dangerous substance and can cause lung cancer. However, there has not been any case of death or lung cancer in asbestos cement plant in India. One of the studies conducted in 2004-05 by Central Labour Institutes of the Ministry of Labour, Govt of India, has not found any asbestos-related diseases in 8 factories.   Nor is there any evidence to show that people who lived under the asbestos cement roofing - even for decades - have had any adverse health effects.

The various inspections and studies of the government agencies from time to time and the health records of employees, including the retired employees has been the testimony to the claim that manufacture and use of asbestos cement products are not a health hazard to the employees or the users. All the production facilities are fully automated where the workers have no direct exposure to asbestos fibre. Workers have no chance of inhaling the fibre as the fibres are bound to cement, besides, workers are provided with all kinds of precautions like masks, in addition to proper environment engineering controls.

When it comes to products asbestos cement such as corrugated roofing sheets, pipes, etc. the asbestos fibers are bonded with cement and have no chance of getting airborne and polluting the environment. 

It can thus be concluded that Chrysotile asbestos is just as safe, if not safer, than the replacement products. There is no proof to the contrary, from either a scientific or a medical point of view. Chrysotile makes it possible to offer families roofs that are well built, safe, and affordable and that will not go up in smoke or be perforated by rust after a few years. Asbestos sheets provide a safe, heat protective, least-noisy roof to millions of poor people, farmers and their poultry and cattle. These are cost effective, durable and energy efficient. AC products serve the developing countries by providing durable and low cost house roofing’s and water pipe systems.

Source: http://www.allvoices.com/contributed-news/7471101

Asbestos - The most expensive word in history

One of the most conspicuous features of our modern world has been the 'scare' or you may call it "hysteria" - some threats to human health get vastly exaggerated, provoking a hugely costly economic, social and political mayhem.

We analyse many of the major scares of recent years, showing how they follow a remarkably consistent pattern.

A crucial part in almost every scare is played by supposed scientific experts who misread or even manipulate the evidence, usually by putting two things together and theorising, wrongly, that they are linked. (Scientific studies in the recent times also get directed by vested business/product promoters' interests.   Examples:  Some say milk is good and essential.   Other studies say it is NOT.   Some studies say Eggs are great for health.  Others say - eggs may better be avoided).

A classic instance of this has been the great scare which has swept the Western world in recent decades over asbestos, based, as it turns out, on a fundamental scientific confusion which has cost businesses, homeowners, insurance companies and  economies in the Western world (especially USA) truly astronomic sums.

Most people these days imagine that asbestos has been identified as one of the most dangerous substances in the world, and that even the slightest contact with its 'deadly fibres' can cause cancer.

They might be startled to know that more than 90 per cent of this alarm is wholly unfounded. This is because the unscientific term 'asbestos' is used to describe two different minerals, with quite different properties.

On one hand are what are known as 'blue' and 'brown' asbestos or 'amphiboles'. These are iron silicate, the hard, sharp, acid-resistant fibres which can accumulated in the human lung over many years, causing two very nasty forms of cancer.

On the other hand is the very much more widespread white asbestos or chrysotile. This is a magnesium silicate, chemically similar to talcum powder, the soft, silky fibres of which dissolve so readily in the lung that their half-life is only 11.4 days.

By far the commonest use of white asbestos is as a binding agent used with cement to make a wide range of products - mostly roofing sheets and drinking water pipes. The fibres holding the cement together undergo a chemical change which makes them no longer respirable by the lungs at all.

The essence of the great asbestos scare has been that the genuinely dangerous properties of the amphiboles have been projected onto white asbestos, which in manufactured form, poses no measurable risk to health whatever (like any dust, such as flour, chrysotile is only dangerous when workers are exposed to its raw fibres in very high doses).

The alarm over asbestos began in the early 1960s when a much higher than normal mortality rate was discovered in US shipyard workers who had been exposed to very high concentrations of amphiboles (blue and brown asbestos, because of their acid-resistance, were extensively used for insulation in shipbuilding).  Asbestos-excess-inhalation-related diseases may manifest in a human being after 15 to 20 or even 30 years from the initial exposure. Particularly when it was revealed that manufacturers had long been suppressing evidence of the damage inflicted on workers, this led to a fast-growing avalanche of compensation claims.

And it was at this point that the confusion between the different forms of asbestos crept in, a basic error which the lawyers and more alarmist scientists did nothing to discourage.

By the end of the 1980s these soaring compensation claims were becoming a major threat to the global insurance industry (in the early 1990s they brought Lloyds of London to its knees).

The panic over asbestos was now so great that in 1989 the Environmental Protection Agency (EPA) tried to ban its use in the USA altogether, making no distinction between amphiboles and chrysotile.

In 1991 the federal courts reversed the proposed ban on white asbestos, stating that, on the EPA's own data, it was likely to cause many fewer deaths than 'the ingestion of toothpicks'.

By now, however, the panic had given rise to two separate commercial scams, both immensely lucrative. The first was being run by the compensation lawyers, who by now had brought hundreds of thousands of claims, the vast majority of which, as eventually emerged, were bogus (a celebrated expose in Fortune magazine dubbed it 'The $200 Billion Miscarriage Of Justice').

The other scam was worked by the new profession of licensed contractors who, under new laws on both sides of the Atlantic, were now alone legally permitted to work with asbestos. This enabled them to exploit the general fear and confusion by charging absurdly inflated sums for removing supposedly 'deadly' asbestos from buildings, more than 90 per cent of which was in fact harmless.

The colossal sums of money now at stake had called into being a powerful political lobby, supported by the law firms and contractors, along with the multi-national manufacturers of asbestos substitutes, who had a vested interest in perpetuating the confusion between the different types of asbestos; and in 1999 they won a signal victory in persuading the EU to introduce a total ban, making no distinction between amphiboles (long since been withdrawn from the market) and chrysotile.

On the back of this muddying of the scientific and legal waters, the various commercial interests have continued to enjoy an extraordinary bonanza, ripping off the public on both sides of the Atlantic on a colossal scale.

When in 2002 Britain's Health and Safety Executive introduced new regulations to comply with EU law (flatly contradicting studies carried out by the HSE itself), its original estimate for the cost of implementation was £8 billion, making it one of the two most expensive laws ever put on the UK statute book.

Subsequent evidence of the alarming scale on which HSE-licensed contractors have continued to exploit their privileged position, by grotesquely overcharging for work often not necessary at all, suggests that even this was a serious underestimate.

Only in the past few years have a series of new studies by some of the world's leading independent scientific experts on asbestos (such as Dr David Bernstein, Professor Fred Pooley and Dr John Hoskins) finally confirmed in exhaustive detail just how insignificant is the danger which chrysotile poses to human health.

But by now, thanks to that basic linguistic confusion, the damage has been done - making 'asbestos' arguably the single most expensive word in history.

Asbestos Diseases

Asbestos inhalation in excessive doses for a prolonged period can result in 3 types of diseases, namely, respiratory problems leading to  Asbestosis,  Mesothelioma lung cancer and other respiratory 

It has been found in various scientific studies that Mesothelioma is associated with the use of Blue asbestos known as Crocidolite.   It has been observed that only Chrysotile type White Asbestos is used within stipulated pollution control levels, these diseases can be prevented.

According to (Environmental Health Criteria) Document No. 203, a World Health Organization's publication of 1998, Asbestosis occurred only at exposure levels of 5 to 20 fibres per cubic centimeter of air over a period of 40 years.   

The exposure levels in the asbestos-cement factories in general has been  well below 0.5 fibres per cc and has progressively been brought down to 0.1 fibre/cc with stringent pollution control systems.   This level renders asbestos absolutely harmless.  The Factories Act in India, stipulates a safe level of 1 fibre per cc.

Even at construction sites where ac roofing sheets, etc are installed with the help of hand-driven tools, dust concentrations were noted to be less than 0.1 fibres per cc.

It may be concluded that chrysotile asbestos fibres can be used quite safely without harming the workers in the ac factories or general public or the surrounding environment.

Who Wins if Asbestos Cement is banned ?

The Indian asbestos-cement (AC) industry comprises of  AC roofing sheet production ( 90% ) and  AC Pipe production (10%).  This industry, with an annual turnover of Rs.4,500 crores  contributes about Rs. 800 crores to the State exchequer.  It employes over 1,00,000 people directly and over 2,00,000 people indirectly.   From a modest beginning  75 years ago,  the current estimated annual production is 4.2 million tons of AC sheets and pipes in the organized sector.   In the recent years, the AC sheet production has been rising at the rate of over 10% each year.   This reflects the demand for these products which are economically and durability-wise much more beneficial than the other  alternatives such as GI Sheets, Galvalume Sheets, PVC Pipes, Steel Pipes, Ductile Iron Pipes, etc. etc.

So, why is there a negative propaganda and emergence of a band of anti-asbestos activists whose sole aim is to get a ban on asbestos and elimination of asbestos based products ?  And who gets benefitted if the AC sheet and pipe industry is eliminated ?

A combination of vested commercial interests and ignorance of facts, is the cause for this propaganda.  If asbestos cement products are banned, the Metal and Man Made Fibre industries will sell an additional 4.2 million tons of their products (by taking over the AC sheet business).  In fact the figure will be larger as the weight per sq mtr of metal products is more than AC products.  When you consider a global ban on AC products, the gain for competing industries will be multi multifold.

To achieve their goal of removing asbestos products from the world, these  alternative product industries, have been, through the created NGOs, such as International Ban Asbestos Secretariat,  Indian Ban Asbestos Network, and other associated, affiliated individuals, spreading misleading information - claiming that asbestos was one of the most dangerous substances in the world - When you ask for evidence of health problems, in the recent years, country-wise or sector-wise,  these anti asbestos activists (AAAs) have no tangible answer.

Regardless of the synergies and unrelenting campaigns by the AAAs,  the Govt of India, having obviously been convinced that AC production  can be maintained in complete safety with due precautions, is allowing the industry to grow to serve the needs of the country.   The GOI's response is the last word on the subject.

Mine Jeffrey Accepts Offer from Canadian-Led Investors

Guarantees Safety, Responsible Use and Jobs 

MONTREAL, Nov. 1, A Canadian-led consortium of international investors has made a successful offer to buy 100% of Quebec's privately held Mine Jeffrey Inc. All shareholders, including the workers' coop, have approved the offer. The parties hope to close the transaction by the end of the year and to resume work on the underground mining project. 

Mine Jeffrey's modern facilities have an excellent reputation for safety. The open pit operation has been in business for more than 130 years.

The consortium, which includes investors from India, will finance the completion of an underground mine project initiated several years ago. This will enable the company to produce approximately 225,000 tons of chrysotile fibre annually, while certifying safe and responsible practices from cradle to grave.   

The consortium has committed to provide a stable supply of its high-quality fibre—but only to large companies certified for safety and environmental responsibility. This will protect workers' health and safety, as well as strategic commodity requirements in Asia, the world's largest market for the product. 

This investment will secure 500 jobs in Quebec for the next 25 years, in a region that is currently economically depressed; it will also maintain Canadian control over an important commodity.  

According to Bernard Coulombe, President and Principal Shareholder of Mine Jeffrey, "The new investors will not be involved in the day-to-day running of the company, which will be entrusted to the existing management and workers."   

Michael Vineberg, senior partner at Davies Ward Phillips & Vineberg and legal advisor to the investor consortium, said that "Mine Jeffrey will remain under Canadian control. The controlling interest in the consortium will be held by Canadian investors. They are looking forward to working with Monsieur Coulombe and current management."  

Chrysotile fibre is currently used legally in Canada, the USA, and countries in South America and Asia.  

Chrysotile fibre is used in developing countries predominantly to manufacture affordable and sturdy roofing sheets and pipes. A small percentage of chrysotile fibre is mixed with cement, thus binding the fibre. None of the fibre produced at Mine Jeffrey is used in loose form, as was the case in legacy environments, and as may still happen among smaller companies that would not qualify as buyers of Jeffrey's product.

Chrysotile fibre was first discovered in Quebec in 1876. There are currently two producers in the province.  

Chrysotile fibre, previously known as asbestos, is classified as a hazardous product. However, like hundreds of other hazardous materials, it is used safely under controlled conditions around the world. 

Source: http://www.newswire.ca/en/releases/archive/November2010/01/c7922.html