|Environmental Handbook Volume II: Agriculture, Mining/Energy, Trade/Industry (GTZ, 1995, 736 p.)|
|Trade and industry|
|54. Mills handling cereal crops|
Large quantities of service air are used for transport, separating processes, heat discharge and aspiration in flour and hulling mills where the process technologies comprise milling and sifting techniques and abrasive and centrifugal hulling. This dust-laden air must be treated, making dust removal from air a priority concern.
Furthermore, the noise produced in such installations must of course also be given due consideration.
When planning mill projects, the various national limits must be taken into account at the design stage; if there are no adequate legal provisions, international standards must be applied. The provisions and limits applicable in Germany are quoted below by way of example.
The following legal standards and technical regulations are valid in the Federal Republic of Germany for the area under consideration:
· Bundes-Immissionsschutzgesetz, Neuauflage (New Edition) 1990
· VDI-Handbuch Reinhaltung der Luft, Band 6;
VDI 2264, VDI 2263
· Arbeitsbler der Abwassertechnischen Vereinigung (ATV), November 1980 Issue
· Biologische Bundesanstalt fd- und Forstwirtschaft
Almost all afterproducts from flour and hulling mills can be recycled in the animal feed industry, are potential sources of energy or can be used as raw products or auxiliary materials in subsequent processing industries (oil mills and breweries, steel industry and foundries).
Emission values for local environmental protection in Germany are those specified in the TA-L (Technical Instructions on Noise Abatement). The guideline of the German Association of Engineers no. 2058 requires noise protection at the workplace, with the issue of personal hearing protection from 85 dB(A) upwards, and the wearing of this protective gear from 90 dB(A). These workplaces should be labelled and compliance with safety measures monitored.
Noise level and air quality measurements in the flour milling industry provide information about environmental impact and the safety measures required to be taken.
Table 2 - Noise levels in mills handling cereal crops
Machine/part of building
Noise level dBA
Separator floor Sifter floor Roller floor Hulling machines Compressors High-pressure ventilators
105 100 105 108 95 100
1000 to 2000 800 to 1200 1500 to 1800 1800 2000 2500
This data shows that not only external noise emissions, but also workplace conditions inside the plant need to be dealt with by effective safety measures22).
22) such as machine enclosures and the wearing of hearing protection.
The Compendium of Environmental Standards provides information on assessment with regard to individual substances.
Where combustible substances are used for drying, only those with a maximum sulphur content of 1.0% are permissible.