Studies on the Gases Emission under High Temperature Condition from Moulding Sands Bonded by Modified Starch CMS-Na

Abstract

Emission of gases under high temperature after pouring molten metal into moulds, which contain the organic binder or other additives (solvents or curing agent), may be an important factor influencing both on the quality of the produced castings, and on the state of environment. Therefore, a comprehensive study of the emitted gases would allow to determine restrictions on the use of the moulding sands in foundry technologies, eg. the probability of occurrence of casting defects, and identify the gaseous pollutants emitted to the environment. The aim of the research presented in this paper was to determine the amount of gases that are released at high temperatures from moulding sands bonded by biopolymer binder and the quantitative assessment of the emitted pollutants with particular emphasis on chemical compounds: benzene, toluene, ethylbenzene and xylenes (BTEX). The water-soluble modified potato starch as a sodium carboxymethyl starch with low (CMS-NaL) or high (CMS-NaH) degree of substitution was a binder in the tested moulding sands. A tests of gases emission level were conducted per the procedure developed at the Faculty of Foundry Engineering (AGH University of Science and Technology) involving gas chromatography method (GC). The obtained results of the determination of amount of BTEX compounds generated during the decomposition process of starch binders showed lower emission of aromatic hydrocarbons in comparison with binder based on resin Kaltharz U404 with the acidic curing agent commonly used in the foundries.

Carboxymethyl Starch/Medium Chain Fatty Acid Compositions: Rheological Changes During Storage and Selected Film Properties

“…Thanks to its cold water solubility and presence of carboxymethyl (─COOH or ─COO − Na + ) functional groups it is widely applied in many branches of industry, for example, textile and paper industry, pharmacy, cosmetics, and environment protection. [1,2] Moreover, its aqueous solutions can be used as binders for sand foundry [3][4][5] wood, [6] drilling mud, [7,8] DOI: 10.1002/star.201900240 or production of electrorheological fluids. [9,10] Viscosity of CMS solutions is a very important factor in many applications and it can be regulated by, for example, optimization of starch etherification parameters, [11,12] slight crosslinking [13,14] or additive incorporation, for example clays, into solutions.…”

Thermoanalytical tests (TG–DTG–DSC, Py-GC/MS) of foundry binders on the example of polymer composition of poly(acrylic acid)–sodium carboxymethylcellulose

“…On the other hand, the use of synthetic resins is associated with their negative impact on the environment like the presence of harmful organic compounds in their composition or using SO 2 or toxic amines in the curing process. In addition, during pouring the mould with a liquid metal, harmful products of thermal decomposition of binders are emitted to the atmosphere [2][3][4][5][6][7][8][9].…”

Archives of Foundry Engineering

“…Starch and its derivatives are also an interesting polymers used in the mold technology [3][4][5][6]. Known starch-based binders meet the specific requirements set by the foundry industry while reducing their negative impact on the environment [7][8][9].…”