More and more attention has been paid to odorous emissions in the last few years, due to less and less tolerance toward industrial emissions, even when non-toxic.
Odor is a first signal of a potentially polluted environment and the matter of odor objectivation has long been a crucial aspect to determine actual olfactometric nuisance and develop technologies allowing for odor abatement in industrial premises.
Production premises that frequently produce malodorous odors fall into various fields of activities, one of them being foundries.
Foundries usually manufacture a series of metal products, either as finished or raw materials - ferrous and non-ferrous - with well defined physical, metallurgical and dimensional characteristics, based on clients’ requirements.
Typically, foundries are classified on the one hand considering the type of metal alloy (ferrous or non-ferrous) and on the other hand considering the type of molding process used (“shape to be lost” or “permanent shape”).
It is necessary to go through many production steps to obtain a part, and these are correlated between them according to a specific sequence. Phases may be related to two main areas:
In this article we will examine Labiotest solution, felt as being adequate from a technical point of view and at the same time economically sustainable for this field of activities, in order to solve problems related to the emission of odorous substances / components.
As all industrial processes, also foundry activities are characterized by the impact related to odors during various production phases and activities performed along the whole production process.
The phases of a production process in a foundry that are really significant as regards odors are:
Among those that may create emissions of odorous components, casting, cooling and molding phases are most critical.
At the time of metal fusion, normally, emission problems regarding odorous substances are located in fuel-operated furnaces, particularly in cupola furnaces, related to coke combustion, or in general in all types of furnaces (used for fusions of ferrous alloys or not) as depending on the quality of scrap used, that can be “polluted” due to oils, fats, or presence of foreign bodies.
Also the molding phase is critical, as regards odorous emissions, especially when opening molds / or going through ejections.
The phenomenon becomes more significant if casting temperature is high and during the opening of molds.
In-depth analyses of odor nuisances situations underlined a problem actually related to phases of ejections in the case of castings having an average size and mass, produced using systems of “green” casting with high quantities of cores made with the help of molding systems in Cold sand and resin boxes.
Reduction of odorous emissions may be meant to reduce emissions at the source, i.e. determining critical production processes that, if optimized, allow for a significant reduction of the impact on the environment in view of a “clean technology”.
To properly deal with the problem and find possible solutions, first of all it is necessary to define and characterize the emission, with the help of an olfactometric investigation, combined with a chemical detailed analysis on site, having as a purpose:
Once the emission has been defined and characterized, it is possible to study the most adequate abatement equipment to deal with the problem.
There are two different ways of performing casting operations:
There are various technologies to use in order to solve odor problems, as for instance washing towers, carbon filters, co-generating units, etc. but difficult to implement at times, because of large areas required and consequent radical changes in layouts making the equipment complex and expensive.
Labiotest solution is an osmogenic barrier allowing for odor reduction through the sprinkling of water mixed with special non polluting neutralizing products, which do not modify the chemical structure of molecules constituting the malodorous substance.
This technology is simpler, as it does not require modifications of the whole plant layout, and is economically more sustainable.
It is possible to use the osmogenic barrier technology both for the treatment of diffused and conveyed emissions:
Hereunder, we are giving some examples of applications in foundries working on ferrous and non-ferrous metals:
The technology to abate diffused emissions through systems spraying water or emulsions with / without additives, is listed as BAT in documents regarding best available techniques (BAT Conclusion) in the fields of ferrous and non-ferrous primary metallurgy.
The problem of reducing mixtures to a low olfactometric threshold is not a simple matter at all.
The choice of an adequate technological solution for specific applications during the various steps of a production process in a foundry requires evaluations on the characteristics of gaseous emissions to be treated, both from the qualitative and quantitative point of view of pollutants, but also in relationship to the flow-rate of gaseous emissions to be treated.
The foundry process phases that originate odorous components, exhaust in the outside environment increased volumes of gaseous emissions, often containing low concentrations of organic pollutants (or odorous components). This aspect is very important to the purposes of the evaluation and choice of the most adequate technology required for the containment of odorous emissions.
The choice of the proper ventilation / suction system must be made considering each single case depending on:
Some plants have forced ventilation systems allowing for the containment of pollution sources without needing hoods, barriers or special structures to separate the area; other solutions consider setting-up specific structures for the containment of pollution sources with fixed and / or movable hoods, where to connect the suction duct for the conveying of harmful substances to disperse in the atmosphere.
The technology for the treatment of polluted air, before it is exhausted in the atmosphere, has to be evaluated considering requirements regarding air “quality” as of recent standards concerning odorous emissions. This implies controlling all gaseous emissions characterized by the presence of organic (and inorganic) mixtures, which, in most situations nowadays, may be conveyed by gaseous flows having a more or less high volumetric flow-rate. They need to be treated anyhow, in order to get purified before being exhausted in the atmosphere.
Apart from legislative compliance, the problem of containing emissions that might cause odor nuisance, must be dealt with and solved in view of the sustainability of foundry activities.
The “social responsibility” of a company requires more and more attention to be paid to environmental problems, as an answer to the matter of quality of life in the territory where it is operating; a responsibility that requires dealing with matters related to odors coming from its activities, using knowledge and technologies available today.