The Chemometric Study of Limestone Physico-chemical Properties and Thermal Behavior for Application in Construction Composites

The limestone, as an economically sustainable and easily available basic raw material, is frequently utilized in the building industry for resolving of the environmental protection issues. The limestone is incorporated in a cementitious system either by grinding with cement clinker, or by blending with the binder during concrete production. The employing of powdery limestone as partial cement replacement gives the construction composites with properties comparable to that of conventional concrete. The study of limestone thermal behavior and its chemistry is crucial for the prognosis of the designed composites properties. In this work, the instrumental techniques (atomic emission spectroscopy, differential thermal and thermo-gravimetric analysis, Fourier transform infrared spectroscopy) and the Principal component analysis were employed to discriminate and classify 22 limestone types. The PCA statistical method, as a means of spectra and experimental data fingerprinting, grouped the samples in a multi-dimensional factor space producing four graphical prognosis - one for each instrumental method. DTA/TG peak values varied the most in a short range between 830-870 degrees C, while FTIR spectra showed the highest diversity in the 867-887 cm(-1) and 1237-1647 cm(-1) ranges. This research was governed by an idea to reveal whether it is possible to differentiate various limestone types and to predict the possibility of their employment in construction composites on the basis of the results of instrumental and mathematical analyses

Cavitation erosion resistance of basalt

The cavitation erosion resistance of the basalt samples from Vrelo, Kopaonik deposit was investigated. The cavitation erosion test was performed using an ultrasonic vibratory cavitation testing method in accordance to the ASTM G32 standard. To measure the cavitation resistance, a change in the sample mass in function of the cavitation time was monitored. The alternations of the samples’ surface morphology with the passing time were analyzed by scanning electron microscopy. The level of the surface degradation was quantified using image analysis software. The results indicate that basalt posses a good cavitation resistance, which implicates that this raw material can be utilized in extreme exploitation environment

Ponašanje mikrolegiranog čelika u uslovima dejstva kavitacije

Mikrolegirani čelici se primenjuju za izradu različitih elemenata opreme u metalurgiji i rudarstvu. Zbog zahteva koje oprema treba da ispuni i sigurnosti koju treba da obezbedi, vrše se različita ispitivanja ove vrste konstrukcionih materijala.U radu je ispitivano ponašanje mikrolegiranog čelika S355M u uslovima dejstva kavitacije. Za ispitivanje je primenjena ultrazvučna vibraciona metoda sa stacionarnim uzorkom. Praćena je promena mase uzoraka u funkciji vremena dejstva kavitacije.Morfologija oštećenja površine analizirana je primenom skenirajuće elektronske mikroskopije.UtvrĎen je mehanizam nastajanja i razvoja oštećenja površine uzoraka pod dejstvom kavitacije.Procenjena je mogućnost primene ove vrste materijala u rigoroznim uslovima eksploatacije koji su prisutni u metalurškim procesima

KAOLIN RECOVERY FROM PROCESSING TAILS

Research and development program was undertaken to develop a new technology for kaolin recovery from final processing tails. The technology combines granulometric separation in laminar flow and gravity classification in hydrocyclones. The three stages granulometric separation flowsheet includes Airlift separator, Reflux classifier and cluster of hydrocyclones. The full scale units were trialed in Vetovo processing plant of Kaolin AD for recovery kaolin from technological waste. Different variables technical and technological parameters are tested. The test data clearly demonstrate that the new tree stage technology is suitable for Bulgarian kaolin industry. The content of Al2O3 increases from 6 – 9 % in technological waste to over 30 % in the final kaolin product. There are possibilities to increase the kaolin recovery. The new technology was introduced in Vetovo processing plant decreasing the losses of kaolin in final tailings

Chassis loading investigation of two-shaft shredder for construction waste management

Recycling industry development need cracked materials with different composition and characteristics. New constructions shredders creation, their engineering design, development through adequate mechanical-mathematical models and practical realization determines the actuality of this paper. The materials crushing for recycling solves important environmental tasks related to environmental protection. The two-shaft hydraulic shredder realized the first and the second stage from the crushing (disintegration) process. Disintegration as part of the recycling process can be successfully applied to the domestic and industrial waste processing, singleand multi-component materials crushing, and to secondary raw materials grinding. The paper is dedicated to the emerging loading of the two-shaft shredder chassis and the resulting calculations and verifications. In the present work has been performed a modeling study of the chassis for such type of shredder for concrete, rubber, plastic and wood crushing. The studies of the mechanical load and behaviour of the chassis have been conducted. The equations characterizing the mechanical processes in the working conditions by the finite element method are solved. For this purpose has been generated a chassis three-dimensional geometrical model, which has been discretized to a planned network of finite elements in the ANSYS MECHANICAL APDL programming environment

STUDY OF TWO-SHAFT SHREDDER FOR CRUSHING OF CONCRETE, RUBBER, PLASTIC AND WOOD

This work presents two-shaft shredder for concrete, rubber, plastic and wood crushing. The existing machine structures have been described, and classification has been made. Analysis of their advantages and drawbacks was performed. Conclusions about the selection criteria for the machines, as the main equipment for technogenic and construction waste recycling, have been made. The paper also presents calculation results and verification of the shredding shafts and chamber of a two-shaft shredder. Modeling analysis of the shredding shafts and chamber has been performed. The studies of the mechanical load and behavior of the shredding shafts and chamber have been conducted. For this purpose, there has been generated a three-dimensional geometrical model of the shafts and chambers, which digitized a planned network of finite elements in the programming environment of ANSYS MECHANICAL APDL

BARITE FLOTATION CONCENTRATE FROM KREMIKOVTZI “BLACK” TAILINGS

The main objective of this work is to prove the perspectives to obtain good quality barite concentrate from technological tailings (called “black tailings”) of “Chelopechene” Tailings Pond. They had been accumulated by 1989 when magnetizing roasting technology had been used in Kremikovtzi processing plant. Grindability and floatability studies of “black tailings” were performed. Laboratory flotation tests were carried out. The test data show that the “black tailings” could be beneficiated by flotation with suitable selection of reagents. The high quality barite concentrate with BaSO4 content over 95 % and Fe – from 0.82 to 1.52%, at BaSO4 recovery over 64 % could be achieved by using collector reagent ALP 611 or reagent mixture OMC 199 with Chemopen 3467 and ALP 611 with OMC 199 at ratio 3:1 and collector reagent dosage 600 g/t. The quality characteristics of the produced barite concentrate meet the international standards of class “A” and “B”

UTILIZATION OF CONSTRUCTION WASTE AS RAW MATERIAL IN MANUFACTURING OF GYPSUM-BASED COMPOSITES

This paper presents a laboratory investigation of new application opportunity of building waste materials and potential usage as a component in production of gypsum based building materials. Production of new type eco-friendly gypsum based composites was studied as a potential utilisation sector. The main focus is directed on gypsum binder mixture properties examination with different proportion of incorporated construction waste materials 5-45%. It was designed and tested fresh state behaviour of gypsum-waste mixture and specimens in standard water/binder ratio. Construction waste material is a fines obtained by combined crushing-sorting installations. Slump flow test of gypsum-waste suspension and dry samples characteristics as compressive and flexural strength, water absorption and shrinkage were tested. On the basis of the obtained results, it was established that the prepared gypsum-waste mixture is an alternative for the production of gypsum based building products. Using the tested mixture in manufacturing processes lead to reduction in the energy and water consumption

TAILINGS CHARACTERIZATION OF "CHELOPECHENE" TAILINGS POND

The composition of Kremikovtzi deposit is complex. The main component is iron and secondary components are barite, lead, manganese. The beneficiation in the Mineral Processing Plant by 1990 year included magnetizing roasting and is produced iron and barite concentrates. The technological tailings (called „black tailings“) are stored at “Chelopechene” Tailings Pond. The black tailings were characterized. The data from laboratory tests indicate that this tailings product is suitable to be used as raw material for flotation recovery of barite if an appropriate technology is developed

The chemometric study of limestone physico-chemical properties and thermal behavior for application in construction composites

The limestone, as an economically sustainable and easily available basic raw material, is frequently utilized in the building industry for resolving of the environmental protection issues. The limestone is incorporated in a cementitious system either by grinding with cement clinker, or by blending with the binder during concrete production. The employing of powdery limestone as partial cement replacement gives the construction composites with properties comparable to that of conventional concrete. The study of limestone thermal behavior and its chemistry is crucial for the prognosis of the designed composites properties. In this work, the instrumental techniques (atomic emission spectroscopy, differential thermal and thermo-gravimetric analysis, Fourier transform infrared spectroscopy) and the Principal component analysis were employed to discriminate and classify 22 limestone types. The PCA statistical method, as a means of spectra and experimental data fingerprinting, grouped the samples in a multi-dimensional factor space producing four graphical prognosis - one for each instrumental method. DTA/TG peak values varied the most in a short range between 830-870°C, while FTIR spectra showed the highest diversity in the 867-887 cm-1 and 1237-1647 cm-1 ranges. This research was governed by an idea to reveal whether it is possible to differentiate various limestone types and to predict the possibility of their employment in construction composites on the basis of the results of instrumental and mathematical analyses. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. ON 172057, III 45008, TR 31055, TR 34006, and TR 34013