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Waste Rubber Recycling
Published in Anil K. Bhowmick, Current Topics in ELASTOMERS RESEARCH, 2008
Anandhan Srinivasan, A.M. Shanmugharaj, Anil K. Bhowmick
In the cryogenic process, precooled, embrittled rubber is fractured using high strain rates (e.g. with swing or fixed-hammer impact mills) [8,37–41]. Liquid nitrogen is used to cool the rubber to very low temperatures (i.e., below the glass transition temperature of the rubber). The main advantages of this method apart from cost-effectiveness are low power requirements, improved flow characteristics, and easy segregation of metal, fabric, and powder. For the production of finer mesh-size powders, cryogenic grinding seems to be more economical than ambient grinding. Since less heat is generated in the cryogenic process, polymer degradation is also minimized. In the case of cryogrinding technique, the particle size obtained is smaller and the size distribution is narrower than that obtained by the ambient grinding technique [26]. In cryogrinding technique, the level of oxidation that occurs on the rubber surface is low and hence fine rubber powder can be obtained.
Cryogenic Processing Of Foodstuffs
Published in Norman R. Braton, Cryogenic Recycling and Processing, 1980
The use of liquid nitrogen for cryogenic grinding offers many advantages when compared to standard grinding methods that do not use any low-temperature refrigerant. Some of the more common benefits are listed in Figure 14 and are described as follows:
Improving fracture and moisture resistance of cold mix asphalt (CMA) using crumb rubber and cement
Published in Road Materials and Pavement Design, 2022
Dana Daneshvar, Arash Motamed, Reza Imaninasab
Ambient and cryogenic grinding are the two major manufacturing methods for CR production. Although both can produce CR particles with similar size distribution, each grinding method gives a significantly different CR surface texture. In the cryogenic grinding, the scrap tyres submerge in the liquid nitrogen and the milling process is done at extremely low temperatures, below the glass transition temperature of the scrap tyres. This leads to CR particles with smooth and glasslike surface and also lower surface area (Fontes et al., 2010). On the other hand, in the ambient grinding process, the scrap tires remain at room temperature throughout the screening and cracker milling process. This leads to CR particles with rough surface, irregular shape, and large surface area (Blumenthal, 1996). Lee et al. (2008) indicated that the CR produced by the ambient grinding results in more effective rubberised binder with regard to rutting and low temperature cracking resistance. Shen et al. (2009) showed that the higher surface area of the ambient CR leads to much greater complex modulus and phase angle of the CR-modified binder. Therefore, having higher efficiency in improving performance as well as easier processing, ambient grinding was deployed to manufacture the CR. The specific gravity of the CR used in this study was 1.135 g/cm3 and its chemical components are listed in Table 3.
A comparative analysis of grinding of AISI D2 tool steel under different environments
Published in Machining Science and Technology, 2022
Ashwani Sharma, Mohd Zaheer Khan Yusufzai, Meghanshu Vashista
Cryogenic grinding is used to grind the workpiece material throughout higher wheel speeds, moreover to obtain lower forces, better surface property and enhanced surface integrity, including increased grinding performance and decreased overall costs. Proven advantages of cryogenic grinding are:developed method sustainability (environmentally secure and clean cooling);reduced forces due to the sharpness of grits;more wheel life because of lesser abrasion and friction;better product property in machined sections due to less adhesion of material;improved surface integrity throughout the controllable behavior of microstructure and phase variations;
Recycling spent lithium batteries – an overview of pretreatment flowsheet development based on metallurgical factors
Published in Environmental Technology Reviews, 2023
Gholamreza Khodadadmahmoudi, Kourosh Javdan Tabar, Amir Hesam Homayouni, Saeed Chehreh Chelgani
Cryogenic grinding (freezer milling) is the act of cooling materials (dry ice, liquid carbon dioxide, liquid nitrogen, and the mixture of CO2 and argon) and then cutting freeze samples into smaller pieces. This process was invented since thermoplastic materials are challenging to crush at ambient temperatures (softened, adhere in lumpy masses, and might clog screens) [35, 57, 64–66]. Through this process, the crusher is sealed, and the cooling material is inserted to fill it [35, 58]. An inert gas environment consumes more resources; thus, it is mostly out of interest, and wet processing is still the first environment chosen based on discharging and downstream processes [27].