Hydrogen Fluoride Producers and Users Sector Group

Purpose:
To ensure that, as responsible producers and users of hydrogen fluoride, our position on health, safety and environmental matters, regulatory affairs, transportation and handling is understood. The Group will seek to have those issues dealt with on technical merit.

The sector group will seek to:

• set policy and direction for HF producers and users on health, safety and environmental matters
• establish and communicate current 'Best Practice' for handling HF
• provide informed communication to UK government and civil service and the European Commission
• anticipate safety concerns and act accordingly
• provide a forum for technical communication between HF producers and users
• actively liaise with other groups, including UK, and European and US based organisations.

Members:
Chairman: Mr D McGreal, Ineos Fluor Ltd

Mr P Alderman, BP Oil Grangemouth Refinery Ltd

Mr S Barley, Conoco Ltd

Mr J Edwards, Laporte Fluorides

Mr M Hoile, BP Oil UK Ltd

Mr J Holmes, BNFL plc

Mr P Kaufman, BP

Mr I Kerslake, Rhodia Organique Fine Limited

Dr S Lynch, Laporte Fluorides

Mr P Martin, Shell UK Ltd

Mr W D Monk, BP

Mr M Muller, Texaco Refinery

Mr R Rogers, Avecia Ltd

Mr E E Scriven, Shell UK Oil Products Ltd

Mr J Smith, Conoco Ltd

Mr P V Ward, Avesta Sheffield Ltd

Mr S Whittle, F2 Chemicals Ltd

CIA staff member:
Mrs E Surkovic (Secretary)

Hydrofluoric acid
Characteristics of Hydrofluoric acid

1. Weak acid
2. Highly undissociated (e.g. 1000X more undissociated than hydrochloric acid)
3. Highly lipid soluble (i.e. able to penetrate biological membranes such as skin easily)
4. Found in both anhydrous and aqueous forms. The aqueous form is colourless.

Properties
Liquid, colourless, fuming, mobile liquid, miscible with water. Will attack glass and any silica - containing material. Non-flammable.

Cas No 7664-39-3.

Uses

1. First used to etch glass in 1670
2. Present industrial uses
   • propellants and solvents
   • insecticide and fertilizer production
   • manufacture and reduction of aluminium oxides and chlorides
   • brewery: control of fermentation
   • etching and frosting glassware
   • fabric industry: stain removal
   • leather industry: tanning
   • welding and stainless steel pickling
   • production of high octane fuels
   • drug and dye production
   • manufacture of semiconductors

Annual production
UK 40 000 tonnes

World 400 000 tonnes

Manufacture
Fluorspar (CaF2) is the principal industrial source of fluorine and hydrochloric acid manufacture. It is widely distributed in workable deposits throughout the world - particularly in China, Mexico and Western Europe. Annual world production exceeds 4 million tonnes. The UK production is 100 000 tonnes, from deposits in Derbyshire and Durham.

Fluorspar (60-80% calcium fluoride) is concentrated to 98% by flotation techniques to obtain the "acid-grade" material. Silica is the principal impurity and is removed.

The acid-grade fluorspar is mixed with preheated 98% sulphuric acid and oleum, and the resultant slurry is fed continuously into large, rotary steel kilns where it is heated to 600 K for several hours.

CaF2(s) + H2SO4(I) CaSO4(s) + 2HF (g)

A typical kiln is up to 50 metres long and can produce 10-20 000 tonnes per annum.

The gases, mainly hydrogen fluoride, emerge from the bottom of the horizontal kiln, and are fractionally distilled in a column, termed the pre-scrubber. It is partially condensed to provide reflux to the pre-scrubber column. Solids and sulphuric acid are removed and the hydrogen fluoride vapour is further purified by distillation and condensed to a 99.9% pure hydrofluoric acid.

The gaseous effluent is largely silicon tetrafluoride which, on reaction with water, produces fluorosilicic acid.

SiF4 + 2H20 Si02 + 4HF

SiF4 + 2HF H2SiF6

Calcium sulphate, generated in the manufacture of hydrogen fluoride, is known as synthetic anhydrite or fluoroanhydrite. Less than 30% of UK produced material is sent to landfill. Over the past 10 years a variety of applications have been developed utilising synthetic anhydrite as an essential component. These include the manufacture of aerated concrete building blocks, monolithic cements and floor screeds.

First aid
The HSE have produced a first aid pamphlet.