Why Asbestos was called a ‘magic mineral’?

Introduction

Asbestos is a collective term for several naturally occurring silicate minerals, mined in other countries but used extensively throughout the last century in the manufacture of Asbestos-containing Materials (ACMs). The UK was a major player in such manufacturing, the two main producers being Cape Asbestos and Turner & Newall.

Over six million tonnes of raw asbestos fibres were imported into the UK during the 20^th century, the peak period being the late 1960s and early 1970s when an average of about 150,000 tonnes of asbestos fibres were reaching our shores each year.

Asbestos has many useful properties, which led to it being regarded by many as “the magic mineral”.

• Asbestos is fireproof and will not burn; this led to its use as fire-proof boarding within fire-breaks, fire doors, oven and furnace door gaskets and textiles for protective garments, including suits and gloves.
• Asbestos is an excellent thermal insulator, having a very low heat transfer coefficient.
• ACMs are usually very strong and durable, with the fibres having a high tensile strength, making them ideal for use as reinforcing or binding agents.
• Asbestos has excellent electrical resistance and is a good sound absorber.

One of the main uses of asbestos of relevance to redundant plant was for asbestos insulation (or lagging) in the form of amosite (brown), crocidolite (blue) and chrysotile (white), or mixtures of such types. Asbestos insulation is most often encountered as lagging to boilers and/or pipes. Asbestos insulation can, in the case of hand-applied lagging, contain anything between around 5% to 85% asbestos, and up to 100% (almost exclusively chrysotile) for pre-manufactured textile blankets. Another pre-manufactured form of asbestos insulation, Caposite, contains around 70% asbestos, mainly amosite. Caposite insulation is usually encountered in the form of hemispherical lengths of material applied to either side of pipes and held in place by jubilee clips.

Other types of ACMs often associated with redundant plant include gaskets (CAF joints or rope), electrical switchgear, cables and pipe linings.

Alexander Nicoll CCP (Asb.), AFOH

Senior Consultant, Asbestos Consultants to the Environment Ltd