9th Intl. Symp. on Sustainable Materials Recycling Processes & Products

Rotary Kiln is a rotating cylindrical reactor that reduces the oxide feed minerals or dusts with carbon reductants and/or natural gas in order to extract a specific component from the feed by volatilization and produce a waste oxide material or to preliminary reduce the feed material into a pre-reduced one to be subsequently used in a specific reactor. Because of the specificity of these rotating reactors the number of shutdowns to clean the reactors are numerous and as such they constitute a big source of productivity loss. This work presents a unique control of process operations of rotary kilns, concentrating in one of the most difficult ones, the Waelz Process through the unique proprietary FLOGEN CONTOP design, decision making, control, optimization and automation system that made possible a considerable increase of the zinc recovery by volatilization and a drastic decrease of the numbers of shutdowns. 

According to the Waste Act, a waste is something that the owner wants to get rid of, or the removal of which is necessary from the point of view of caring for a healthy environment. The term secondary raw material is not defined in the legislation, but it is commonly used in practice [1]. It is a raw material that is obtained from waste by various procedures, i.e. it is created by human activity, which distinguishes it from primary raw material that was created by natural processes without human intervention. The condition for treating treated waste to be called a secondary raw material is that there is a demand for it and that it is traded on the producer's side.
Foundry production is accompanied by the creation of a large amount of waste. At each stage of casting production, different types of waste are generated in different quantities. The largest amount of waste is used foundry sand, followed by various fine-grained wastes that arise during melting, preparation of moulding materials, production of moulds and cores, and during processing and blasting of castings [2]. Another important foundry waste is the slag that is created during melting in any furnace equipment.
The current situation in Europe is "pushing" the producers of these wastes to reduce their amount. One possibility is waste recycling [3,4]. Most foundry waste cannot be directly recycled, but with certain modifications, they become secondary raw materials that can be used primarily in construction, agriculture, and partially also in foundries.
This contribution analyses the waste generated in the foundry process and points out the possibilities of their treatment and further use.

Skin is the most vulnerable organ to different kinds of injuries due to its large surface and potential for exposure to biological, mechanical, thermal, and radiation factors. In this context, the demand for innovative biomaterials for chronic wounds, skin burns, or skin disease treatment is high [1].
Collagen is a consecrated biomaterial for different skin wound healing formulations like powders, creams, films, hydrogels, and microspheres, due to high biocompatibility and non-toxicity as compared to synthesis polymers [2]. Recent research reported the advanced efficiency of gelatin and collagen hydrolysate in wound healing as compared to native collagen [1], due to the more available peptides and binding sites for the regeneration mechanism in the wound healing process.
The presentation will explore the potential of gelatins of different origins extracted from bovine and donkey hides, rabbit skin or fish scales to be processes as collagen nanofibers with preserved bioactivity and high efficiency in skin restoration due to the scaffold structure with increased surface area-to-volume ratio as compared to gelatin [3-7].
The main properties of these gelatins such as dry substance, ash and protein content, conductivity, viscosity, and molecular weight will be presented in connection to spinnable properties in view of manufacturing collagen nanofibers for new biomaterials used in wound healing.
The electrospinning parameters for fabrication of wound healing mats based on gelatins of different origins will be presented and the influence of solvents will be highlighted. The antimicrobial properties were improved by adding active substances from essential oils to metal and oxide nanoparticles. Coaxial electrospinning was used for volatile essential oils encapsulation and slow release in interaction with skin wounds.
The properties of collagen nanofibers manufactured from different gelatins will be presented in connection with their specific structure and origin: size dimension and morphology (SEM), surface composition (EDX), antioxidant properties, phenol releasing, cytotoxic concentrations, in vivo biocompatibility, and antimicrobial properties.
Finally, the behavior of gelatin nanofibers as compared to gelatins to preservation treatments by different gamma radiation doses will be discussed.
Different gelatin nanofibers successfully fabricated from different raw materials showed the huge potential for biomaterials innovation as compared to the use of classical native collagen in skin wound healing.

The Concept of Industrial and Innovative Development of the Republic of Kazakhstan for 2021-2025 includes the development of production of rare and rare earth metals among the priority areas. The latter, unfortunately, is associated with the emissions of organic compounds into the environment. To avoid this, it is necessary to purify solutions of rare-metal production from organic pollutants.
Sorption with carbon sorbents of a novel type is considered to be the most effective way of removing organic impurities during the hydrometallurgy process of non-ferrous metals [1]. However, there are no data on the behavior of these sorbents in the hydrometallurgy of rare metals. Carbon sorbents active against the ions of rare, precious and heavy metals have been obtained from the waste of rice and coke production such as rice husk and special fine coke. It is known that activated carbons from rice husk are effective to remove organic pollutants [2-4]. But their production is associated with the formation of secondary waste.
The purpose of the current work is to use rice husk and special fine coke to generate a new selective composite sorbent and resource-saving high-temperature material for use in hydro- and pyrometallurgical sectors of industry.
Carbon and silica-containing components are isolated from the both waste. The carbon components are used to produce a composite sorbent. The silica-containing components are used to produce a high-temperature material. The combination of a finely dispersed rice husk carbon material with a large specific surface area and a more durable, meso- and macroporous special coke carbon material contributes to the formation of a carbon-carbon matrix when obtaining a composite sorbent. The combination of stoichiometric amounts of amorphous silicon dioxide isolated from rice husk, special fine coke ash and original rice husk is used to ensure the formation of highly refractory silicon carbide. The burning of rice husk contributes to the forming of a porous structure of the prepared material. The formation, on the one hand, of highly refractory phases and, on the other hand, of a porous system enhances the strength, durability and thermal insulation properties of the resulting refractory material.
So, rice husk and special fine coke (some of the most common waste types) are promising raw materials for creating a selective composite sorbent of a novel type. In order to ensure the complex processing of special fine coke and rice husk, it seems practical to use silica-containing waste from composite sorbent production mixed with raw rice husk to synthesize a resource-saving high-temperature material.
This research is funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (grant number AP 19677767).

Slags from primary lead industry are well known as potential resource for zinc which is accumulated in the slag during lead smelting. At some of the smelters a subsequent fuming process is installed to recover zinc which is usually present in a range between 4 to 16 %.

However, at many lead producers this is not the case and the slag is landfilled. Out of this, over the years, a huge number of dumps was generated worldwide. The Chair of Nonferrous Metallurgy at Montanuniverstaet Leoben has developed possible strategies to treat such slags in a way that zinc and lead can be recovered and the remaining mineral phase containing first of all typical slag components can also be utilized. These concepts allow a full remediation of a dumpsite or a zero waste treatment of slag from ongoing smelter operations.

The present paper describes the reduction process which is performed under CO₂-neutral conditions, utilizing either hydrogen or charcoal. Furthermore, possibilities for slag modification and optimization are explained, allowing a utilization of the slag in building and construction industry. Results from various test campaigns in lab- and technical scale are discussed.

Finally, an overview of the worldwide potential and some process scenarios including economic considerations are presented.