Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
  • B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/02—Sand moulds or like moulds for shaped castings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
  • B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
  • B22C1/14—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives for separating the pattern from the mould

Definitions

• the carbonaceous material In commercially used moulding materials, the carbonaceous material consists mainly of powdered coal, or alternatively a coal dust replacement.
• a problem associated with this kind of carbonaceous material is that it contains a certain amount, usually about 30% by weight, of volatile compounds (such as VOC - volatile organic compounds), which are set free as the moulding material is heated, and which cause emissions and problems with odour from the foundry plant.
• volatile compounds such as VOC - volatile organic compounds
• these volatile organic compounds have a beneficial effect on the casting performance by reducing the adherence of, for example, the moulding material to the cast object, thus reducing the amount of moulding sand that has to be removed from the cast object in subsequent production stages.
• a carbonaceous additive for moulding materials is known from EP1800771A1 . Further experience has shown that this additive works well for smaller work pieces, such as work pieces having a mass of 10 kg or less, or having a maximum wall thickness of 20 mm or less. In particular, this additive provides a very good trade-off between VOC emission and sand adhesion.
• Coal dust replacement may for instance be used to enhance the surface finish of the product, but does not generally contribute to the lowering of VOC emissions or the sand adherence.
• the coal dust replacement may be selected from a group consisting of carbon containing material such as pyrolytic or lustrous carbon former in solid or liquid form such as asphalt, gilsonite, petroleum destillates, organic polymers, dextrin, and starch.
• carbon containing material such as pyrolytic or lustrous carbon former in solid or liquid form such as asphalt, gilsonite, petroleum destillates, organic polymers, dextrin, and starch.
• an additive according to the first aspect in a process of casting a part of iron having a mass of 10 kg or more, preferably 20 kg or more, 50 kg or more or 100 kg or more.
• a moulding material comprising:
• the additive may be added in an amount providing a carbon content in the range of 1.5 to 4 % by weight of the moulding material.
• carbon content is thus meant the measured carbon content in the moulding material, a measurement which is routinely performed in a foundry, usually before every casting cycle to ensure a reproducible result of the casting and the quality of the casting.
• the amount of additive needed in the moulding material will be dependent on factors such as for instance sand to metal ratio. The skilled person would be able to recognize this and know how to calculate an appropriate addition of the carbonaceous material additive.
• pit coal is also meant powdered coal, or coal dust.
• Pit coal in this respect may also be called sea coal, or be of similar types of coal that comprises around 30 % volatile organic compounds.
• EP1800771A1 it was shown that a conventional foundry sand having mainly pit coal/coal dust replacement as the carbonaceous material gave very high emissions of VOCs, but also exhibited very low sand sticking (see sample 3 of EP1800771A1 ). In contrast a foundry sand where the carbonaceous material consisted of only coke, gave very low VOC emissions, but on the other hand high amount of sand sticking (see sample 1 of EP1800771A1 ). In EP1800771A1 it was further proved that a carbonaceous material comprising powdered pit coal and coke, with coke as the main constituent of the carbonaceous material, gave not only reduced VOC emissions, but also an acceptable level of sand sticking or sand adherence. The carbonaceous material additive as disclosed in EP1800771A1 has showed to be in particular efficient for smaller work pieces.
• the carbonaceous material may also comprise coal dust replacement, preferably in an amount of 20 % by weight of the carbonaceous material or less.
• the amount of coal dust replacement may be less than 10 % by weight, preferably less than 5 % by weight or less than 2 % by weight.
• the coal dust replacement may be selected from a group consisting of carbon containing material such as pyrolytic or lustrous carbon former in solid or liquid form such as asphalt, gilsonite, petroleum destillates, organic polymers, dextrin, and starch.
• the organic polymer may be for instance polystyrene.
• the carbonaceous material added to the foundry sand comprised 40 % by weight of the carbonaceous material coke, and 60 % by weight of the carbonaceous material pit coal or powdered (pit) coal.
• the VOC can be measured using different types of measurement methods known to the skilled person.
• One such method is by using FID instruments (gas chromatography with flame ionization detector) or by using so called Tenax ® tubes followed by analysis with gas chromatography and mass spectrometry (GC-MS).
• the FID instruments measures the total VOC emission, including methane.
• Tenax tubes may further allow for analysis of the various hydrocarbons except for the lightest such as methane and can be used as a complement in a measuring process.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Mold Materials And Core Materials (AREA)

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Publications (1)

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Citations (3)

• 2016
  • 2016-02-17 SE SE1650208A patent/SE1650208A1/en not_active IP Right Cessation
• 2017
  • 2017-02-10 EP EP17155559.2A patent/EP3208012A1/fr not_active Withdrawn

Patent Citations (3)

Non-Patent Citations (1)

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