Bányászat és kapcsolódó iparágak hulladékainak szerepe a körforgásos gazdaságban – Urban Mining: Role of the wastes of mining and allied industries in the circular economy – Urban mining

Research of the wastes of mining and allied industries at the University of Miskolc Faculty of Earth Science and Engineering has been carrying out in the Center of Excellence of Sustainable Natural Resource Management in the last decades very intensively. In the present paper the most important industrial wastes are summarized, namely coal mining gangue, fly ash, metallurgical slags, red mud and construction and demolition waste. Moreover, some utilization possibilities are shown briefly from circular economy point of view, i.e. eco-friendly binder, aggregate, cement supplementary material

USPOREDNO ISTRAŽIVANJE MLJEVENJA STAKLENOGA OTPADA PRIMJENOM RAZLIČITIH VRSTA MLINOVA

The present work deals with systematic grinding investigation and determination of grindability of container glass bottles. The systematic grinding tests were carried out in three different kinds of ball mills (a drum mill, a vibrating mill, and a planetary mill) with different energy intensities (low, medium, and high intensity) in dry conditions. In addition, the specific grinding work and specific surface area were determined in every case. The grindability test was performed by the Universal Hardgrove Mill, moreover, the Bond-Work Index was calculated from the Hardgrove Grindability Index. In this research work, the focus was on analysing the grindability of container glass bottles and the goal was energy-efficient milling of glass waste to produce glass foam powder for further utilization (for example glass foam) in a sustainable way. Based on the obtained results, it can be concluded that the optimal milling apparatus for container glass grinding is the drum mill. The reason why is that it has a low specific grinding work (151.52 kWh/t) in comparison with the other two types of mills (3488.37 kWh/t for the planetary mill and 1106.38 kWh/t for the vibrating mill) resulting in a relatively high specific surface area (11314 cm2/g). In the case of grinding industrial quantities of glass waste, the drum mill has a much higher capacity compared to the vibrating mill and the planetary mill.Ovaj rad bavi se sustavnim ispitivanjem mljevenja i određivanjem mogućnosti mljevenja staklenih boca. Sustavna ispitivanja mljevenja provedena su u trima različitim vrstama kugličnih mlinova (bubnjasti mlin, vibracijski mlin i planetarni mlin) različitih energetskih zahtjeva (niskoga, srednjega i visokoga intenziteta) u suhim uvjetima. Osim toga, kod svakoga ispitivanja određena je specifična energija mljevenja i specifična površina. Ispitivanje meljivosti provedeno je pomoću mlina Universal Hardgrove, a Bondov radni indeks izračunan je iz indeksa meljivosti po Hardgroveovoj metodi. U ovome istraživačkom radu fokus je bio na analizi meljivosti staklenih boca, a cilj je bio energetski učinkovito mljevenje staklenoga otpada kako bi se proizveo prah staklene pjene za daljnju uporabu (npr. staklena pjena) na održiv način. Na temelju dobivenih rezultata može se zaključiti da je optimalni mlin za mljevenje staklenih posuda bubnjasti mlin zbog toga što ima nisku specifičnu energiju mljevenja (151,52 kWh/t) u usporedbi s drugim dvjema vrstama mlinova (3488,37 kWh/t planetarnoga mlina i 1106,38 kWh/t vibrirajućega mlina), što rezultira relativno visokom specifičnom površinom (11 314 cm2/g). U slučaju mljevenja industrijskih količina staklenoga otpada bubnjasti mlin ima znatno veći kapacitet u odnosu na vibracijski i planetarni mlin

UTJECAJ SVOJSTAVA SIROVINA NA STAKLENU PJENU OD OTPADNOGA STAKLA

Glass foam tablets were prepared by using mixed glass bottles (green, brown, and white), eggshell waste as a foaming agent, Na-bentonite as binder material, and red mud as an additive, respectively. The influence of the amount of red mud and fly ash on the properties (foaming temperature, mechanical strength, specimen density and porosity, thermal conductivity) of the tablets was studied. The foamed tablets contained 2.5 wt % binder material, 0.1 wt % foaming agent, 5 wt % fly ash, and red mud as additives in different ratios (0 – 40 wt %). After homogenization, the ground raw materials were pressed into tablets at 30 MPa using a hydraulic piston press. The products were heat treated at different temperatures with different heating rates. The final product’s properties were measured (specimen density, thermal conductivity, and mechanical strength through falling and abrasion resistance tests). The most convenient results were shown at 5 wt % red mud in this case, the specimen density and thermal conductivity were the lowest, the values were 0.3 g/cm3 and 0.036 W/mK. If 5 wt % of fly ash was added to the mixture the density value stayed the same, the thermal conductivity increased to 0.048 W/mK, but the mechanical strength of the tablets rapidly increased.Granule staklene pjene pripremljene su korištenjem mješavine staklenih boca (zelene, smeđe i bijele boje), otpadaka ljuske jajeta kao sredstva za stvaranje pjene, Na-bentonita kao vezivnoga materijala uz dodatak crvenoga mulja. Proučavan je utjecaj količine crvenoga mulja i lebdećega pepela na svojstva tako oblikovanih granula (temperaturu pjenjenja, mehaničku čvrstoću, gustoću i poroznost uzorka, toplinsku provodljivost). Granule staklene pjene sadržavale su 2,5% masenog udjela (wt %) vezivnoga materijala, 0,1 wt % sredstva za pjenjenje, 5 wt % lebdećega pepela i crvenoga mulja kao dodataka u različitim omjerima (0 – 40 wt %). Nakon homogenizacije samljevene sirovine prešane su u granule pri 30 MPa uz pomoć hidrauličke preše. Proizvodi su toplinski obrađeni na različitim temperaturama s različitim brzinama zagrijavanja. Izmjerena su svojstva konačnoga proizvoda (gustoća uzorka, toplinska vodljivost i mehanička čvrstoća kroz ispitivanja otpornosti na udar i abraziju). Najbolji rezultati dobivani su kod 5 wt % crvenoga mulja i tu su gustoća uzorka i toplinska vodljivost bile najniže, s vrijednostima od 0,3 g/cm3 i 0,036 W/mK. Međutim, kada se mješavini dodalo 5 wt % lebdećega pepela, vrijednost gustoće ostala je ista, toplinska vodljivost povećala se na 0,048 W/mK, ali je mehanička čvrstoća granula naglo porasla

RAW MATERIALS FOR GEOPOLYMERISATION

Geopolymers are inorganic alumina-silicate materials with excellent physical and chemical properties. Despite being a rather recent research topic, many papers and books have been published focusing on various aspects of geopolymerisation: the history, properties, production, raw materials, applications and development of geopolymers. A brief overview of geopolymer technology is presented in the article, emphasising the great variety of raw materials that can be used for geopolymer production. Considering the variety of the origin of these materials, three categories are distinguished: primary raw materials which consist of natural minerals, secondary raw materials which are industrial wastes and by-products, and wastes and by-products of natural origin. In spite of not being widely accepted by the industry yet, geopolymerisation has the potential to become a valuable waste-recycling technology in the future

Physical-chemical, mineralogical and radiological properties of red mud samples as secondary raw materials

The main goal of the presented research was the preliminary investigation of possibility of red mud (Hungarian dump sites Almásfüzitő (sample A) and Ajka (sample B)) application as a pigment or as a raw material for use in the construction material industry. Also, the aim of this work was the characterization of red mud as industrial waste generated by the Bayer process in the aluminum industry–which may cause environmental problems if appropriate treatment is not carried out. The main mineral phases of both red mud are Hematite (Fe2O3), Calcite (CaCO3), Gibbsite (Al (OH)3) and they consists of particles of average median particle size 2.1m (sample A) and 2.5m (sample B) and have a characteristic red color, which was the reason for its testing for use in the industry of building materials as a pigment for standard concrete mixtures. The content of radionuclides in the samples were determined by gamma spectrometry, and the radiological hazards originated from 238U, 232Th, 40K in the samples, were assessed through radium equivalent activity, external radiation hazard index. Absorbed dose rate (D) and the annual effective dose (E) were calculated in accordance with the UNSCEAR 2000 report and-results are presented in this paper

Mechanical activation of power station fly ash by grinding – A review

Power station fly ash has good application possibilities mainly in the construction industry, nevertheless, significant amount is landfilled due to their relatively low reactivity and heterogeneity. Hydraulic properties of fly ashes can be tailored by mechanical activation achieving a higher added value product, for example supplementary cementing materials (SCMs). The improved properties are higher specific surface area and desired particle size distribution (containing submicron size particles) as well as higher amount of reactive components that can be optimized by grinding. The objective of this paper is to investigate the effect of mechanical activation of fly ash by grinding on physico-chemical and minerological properties. It can be established that there are numerous techniques for mechanical activation of fly ash, e.g. planetary ball mill, vibratory mill or stirred media mill. On the other hand, most of the results reported in the literature are focusing on material related investigations, but beside this, from energetic point of view the process related evaluation has even higher importance

Application Of Self-Organizing Neural Networks For The Delineation of Excess Water Areas

In recent times Artificial Neural Networks (ANNs) are more and more widely applied. The ANN is an information processing system consisting of numerous simple processing units (neurons) that are arranged in layers and have weighted connections to each other. In the present study the possible application of an unsupervised neural network model, the self-organizing map (SOM), for the delineation of excess water areas have been examined. By means of the self-organizing map high-dimensional data of large databases could be mapped to a low-dimensional data space. Within a data set, it is able to develop homogeneous clusters, thus it can be effectively applied for the classification of multispectral satellite images. The classification was carried out for an area of 88 km2 to the south of Hódmezővásárhely situated in the south-eastern part of Hungary, which is frequently inundated by excess water. As input data, the intensity values of the pixels measured in six bands of a Landsat ETM image taken on 23rd April 2000 were used. To perform the classification, three different sized neural network models were created, which classified the pixels of the satellite image to 9, 12 and 16 clusters. By using the gained clusters three thematic maps were created, on which different types of excess water areas were delineated. During the validation of the results it was concluded that the applied neural network model is suitable for the delimitation of excess water areas and it could be an alternative to the traditional classification methods

Szilikát-tartalmú hulladékok együttes hasznosítása = Combined utilization of various silicate bearing wastes

Jelen tanulmány a Föld legnagyobb mennyiségben keletkező ipari hulladékainak jellemzőit és egy hasznosítási lehetőséget ismertet hazai és nemzetközi kutatások eredményein keresztül, nevezetesen erőműi pernye és acélgyártási salakra fókuszálva. A kutatási eredmények azt mutatják, hogy a megfelelő előkészítést alkalmazva és a körülményeket optimálva a nyers alapanyagok eljárástechnikai jellemzőinek (szemcseméret eloszlás, fajlagos felület) megváltoztatásával a geopolimer termékek fizikai és mechanikai tulajdonságai (szilárdság, tömörség) javíthatók. Kutatásaink ugyanis kimutatták, hogy a kémiai aktiválás mellett a mechanikai aktiválás is egy igen hatékony eszköz a tulajdonságok szabályo-zására. Ez azonban megváltoztatja nemcsak a termék fizikai, mechanikai, hanem a szerkezeti, ásványtani jellemzőit is, ezért ezen jellemzők meghatározása is kiemelten fontos feladat többek között a fagyállóság szempontjából