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Appendix to OC 690/13 - Safe operation of batch ball mills used in potteries and allied industries

OC 690/13a
Back to Information Document HSE 690/13

APPENDIX 4: Incidents known to have involved batch BBMS
(paragraph 12)

NoDateSummary
1 1967 Failure to non drive side shaft on recently refurbished mill.
2 1971 Ejection of contents due to hydrogen ignition as operator unloaded mill wet grinding manages ore. Hydrogen production due to action of steel balls against wet steel lining.
3 1973 5' diameter rubber-lined BBM exploded whilst milling manganese dioxide. Over-milling due to operator error.
4 1975 Major failure/explosion from over pressurisation.
Hydrogen explosion due to aluminium ear tags in bone.
5 1980 "Explosion" of 3' 6" diameter rubber-walled BBM. Over pressurisation due to failure of timer to turn mill off. Similar incident had occurred several years before.
6 1981 Major failure/explosion of 7' diameter mill.
Over pressurisation caused by overheating due to lack of water/inadequate venting.
7 1981 Failure of stub shaft/support from fatigue due to age, poor maintenance and wear.
8 1983 5' diameter BBM exploded whilst milling damp silicon. Temperature up to 100C which caused hydrogen evolvement and ignition.
9 1985 Operator's hands trapped by "bung" against loading floor. Mill not vented.
10 1985 Operator's ankles scalded when hot glaze ejected as 'bung' removed.
11 1986 Milling molysdendium disulphate with ammonium bicarbonate. Failure of cooling water supply to casing caused overheating and explosion due to over pressurisation.
12 1986 As 10 below, but drive end of 6' diameter mill.
13 1986 Failure of stub shaft at non-drive end of 7' diameter mill. General fatigue due to age. (Machine 26 years old).
14 1987 Explosion whilst in 6' diameter mill milling barium titanate. Over pressurisation (40 psi) due to addition of "dry ice" which caused carbon dioxide formation.
15 1988 Major failure/explosion from over pressurisation at bone grinding. Believed to be due to lack of adequate water. Bursting pressure estimated 60 psi+.
16 1989 Traumatic failure of concrete support plinth as mill stationary during discharge.
17 1991 Major failure/explosion. Over pressurisation due to heating effect caused by lack of adequate water.
18 1991 Operator splashed with mill contents as removing "bung" 20 hours after short run. Pressurisation with carbon dioxide due microbe action on sawdust contamination.
19 1994 Operator hit in face and eyes with glaze when removing "bung" from 5' diameter mill. Mill running 25 rather than 1 hours.
20 2000 Cast iron end plate blew off 7ft diameter mill after 23 hours milling (near to end of cycle). Resulted in significant damage to the end wall of the building in which the mill was housed.
21 2000 Large part of cast iron end plate blew off 7ft diameter mill, near to end of cycle (~12 hours). From the texture of the product in the mill, the company deduced that virtually no water had been added to the mill.
Updated 2008-05-13