Silo cleaning White hydrated lime / unslaked lime
When cleaning or inspecting unquenched lime silos, there is an increased risk for the user who enters the silo using rope access and rescue equipment.
What is unslaked lime?
As some fans will know from the thriller, unslaked lime decomposes all organic materials.
Excerpt from Wikipedia:
Calcium oxide, also known as burnt lime, quicklime, slaked lime, caustic lime or free lime, chemical formula CaO, is a white crystalline substance that reacts with water while generating a lot of heat. This reaction produces calcium hydroxide (slaked lime) according to the reaction equation CaO + H 2 O ⟶ Ca ( OH ) 2 {\displaystyle {\ce {CaO + H2O -> Ca(OH)2}}} {\displaystyle {\ce {CaO + H2O -> Ca(OH)2}}} is formed. Burnt lime is divided into soft burnt, medium burnt and hard burnt lime.
Problems in occupational health and safety
If a person comes into contact with unslaked lime, the reaction on moist surfaces such as the eye or sweat-wetted skin can be detected after just a few minutes.
A slight tingling sensation on the skin is the first sign, which can lead to severe to very severe burns if left untreated.
Careless employees are at the mercy of this first sign if neutralization is not initiated immediately.
The eyes are particularly at risk when handling unslaked lime. The smallest traces in the air are sufficient to cause irritation, increased concentrations cause the tear fluid to crystallize and can cause serious eye damage.
During technical rope applications, silo cleaning or silo inspections, workers quickly work up a sweat. Inadequate protective clothing can lead to a
Inadequate protective clothing can lead to a massive increase in the skin pH value after a short time, with this alkalized sweat the destruction process on the skin is started and progresses very quickly in just a few minutes.
minutes and progresses very quickly. The resulting skin damage must be treated quickly and urgently in order to avoid permanent skin damage.
Respiratory tracts must be redundantly protected from quicklime. It is imperative that contamination of the respiratory tract is avoided, as serious complications can occur if the respiratory tract is damaged. While the user is in the silo system for silo cleaning, there is a very high volume of dust, which must be collected regularly and consistently. The employee / worker must be provided with various protective systems to ensure that respiratory contamination is thoroughly and reliably avoided.
What the specialist has to look out for!
The problem of aggressive quicklime must be identified during the dynamic occupational safety preparation and risk assessment. Rescue dynamic application criteria determine the feasibility of the performance. An adapted rescue concept must be submitted to the plant operator, as fatal accidents at work and mass casualties have occurred in the past and must be avoided in all cases. The rescue and measures concept must be implemented redundantly and discussed with the plant operator. The plant operator must be informed of the risks during silo cleaning by the technical supervisor.
Unknown risk factors in the occupational safety and rescue assessment must be recorded in advance and discussed with the plant operator.
If external rescue services are required, the rescue services must be given the rescue concept for silo cleaning so that they can influence it and adapt their rescue efforts accordingly.
Finally, it should be mentioned that silo cleaning operations in quicklime plants are high-risk measures that should only be carried out by experienced companies. The risk of a fatal accident at work is not only due to falling, but also to a number of other factors.
This article deliberately omits an explanation of the spillage problem, which will be dealt with in detail in a separate article.
