The input of various resources and energy, as well as the output of finished products and wastes in each casting process stage are involved in the process of Moldless sand casting. Taking energy input as an example, primary and secondary energy such as coal, natural gas and electric energy act on molten iron smelting and other process links in the casting process, and are consumed in the form of active work and heat energy. The input energy needs to consider the factors of each stage, such as the greenhouse gas emissions from the processes of mining, transportation and smelting, that is, the manufacturing and production of raw materials, and the greenhouse gas emissions from the use of energy. Similarly, other input raw materials and output wastes in the casting process need to consider the greenhouse gas emissions generated by manufacturing production and waste treatment.

According to the characteristics of casting process parameters, the types of carbon emissions can be divided into material carbon emissions, energy carbon emissions and unexpected carbon emissions. Material carbon emission refers to the carbon emission generated during the production and use of materials put into use in the casting process. For example, paint, alcohol, pig iron and other disposable materials with irreversible one-time consumption, and recyclable materials such as molding sand and recycled iron. The production carbon emission of recyclable materials will not be calculated repeatedly. Energy carbon emissions include the carbon emissions generated by energy substances such as coal, natural gas and coke in the production process and use process, as well as the carbon emissions converted from the power consumption of auxiliary equipment in the casting production process. Undesired carbon emission refers not only to the carbon emission converted from the power consumption of equipment for the treatment of undesired wastes such as slag and sand ash, but also to the carbon emission caused by chemical changes during the use of materials, such as slag forming agent in smelting process, gas generation of molding sand after pouring, etc. The carbon emission calculation model based on carbon emission equivalent is established by clarifying the consumption of various material resources and the carbon emission coefficient and carbon source generation coefficient function of corresponding materials. Therefore, the carbon emission calculation model of Moldless sand casting process can be expressed as the formula:

Wherein, CMI (M1,…), mn-1 (1- λ i) , Mn) represents the material element set, λ I represents the recovery rate of recyclable materials; Fi (F1,…, FN) represents the set of carbon emission coefficients of material elements; CEI (E1,…, en, F1,…, FN) represents the energy element set, E1,…, en represents the equipment energy element, F1,…, FN represents the fuel energy element; GI (G1,…, GN) represents the set of carbon emission coefficients of energy factors; CUi( ε 1U1,…, ε Nun) represents an undesired feature set, ε Represents the function of undesirable carbon source generation coefficient; Hi (H1,… HN) represents the set of carbon emission coefficients of undesired factors.

The carbon emission coefficient of various substances can be determined through relevant literature, material carrying energy consumption and life cycle software database. The carbon emission coefficients of main energy and substances are from China Iron and steel Yearbook GB / t2589-2008 and relevant research. Among them, upstream enterprises and foundries each bear half of the carbon emissions from scrap steel.

The quantitative calculation of total carbon emission can reflect the impact of unit casting on the environment in the production process. For the batch casting production based on single technology and composite technology, only comparing the total carbon emission can not effectively reflect the low-carbon advantage of a certain technology. Carbon efficiency can reflect production capacity and emission reduction potential. In this paper, the carbon efficiency per unit casting is the ratio of the production efficiency under the casting method (single technology or composite technology) to the total carbon emission per unit casting, which can be expressed as the formula: