Jana Seidlerová

Recycling of blast furnace sludge by briquetting with starch binder: Waste gas from thermal treatment utilizable as a fuel

Steel plants generate significant amounts of wastes such as sludge, slag, and dust. Blast furnace sludge is a fine-grained waste characterized as hazardous and affecting the environment negatively. Briquetting is one of the possible ways of recycling of this waste while the formed briquettes serve as a feed material to the blast furnace. Several binders, both organic and inorganic, had been assessed, however, only the solid product had been analysed. The aim of this study was to assess the possibilities of briquetting using commonly available laundry starch as a binder while evaluating the possible utilization of the waste gas originating from the thermal treatment of the briquettes. Briquettes (100g) were formed with the admixture of starch (UNIPRET) and their mechanical properties were analysed. Consequently, they were subjected to thermal treatment of 900, 1000 and 1100°C with retention period of 40min during which was the waste gas collected and its content analysed using gas chromatography. Dependency of the concentration of the compounds forming the waste gas on the temperature used was determined using Principal component analysis (PCA) and correlation matrix. Starch was found to be a very good binder and reduction agent, it was confirmed that metallic iron was formed during the thermal treatment. Approximately 20l of waste gas was obtained from the treatment of one briquette; main compounds were methane and hydrogen rendering the waste gas utilizable as a fuel while the greatest yield was during the lowest temperatures. Preparation of blast furnace sludge briquettes using starch as a binder and their thermal treatment represents a suitable method for recycling of this type of metallurgical waste. Moreover, the composition of the resulting gas is favourable for its use as a fuel.

Residues from the thermal conversion of waste from the meat industry as a source of valuable macro- and micronutrients.

The increased consumption of meat (including poultry) observed over the last decade has led to the intensification of its production. With the production increase, the amount of generated waste also increases. Appropriate disposal of waste from the meat industry will significantly reduce the amount of such waste and its negative impact on the environment. The paper presents a method for the thermal neutralisation of feathers, poultry litter and meat and bone meal (MBM). Waste incineration was carried out in a stationary electric furnace, at a temperature varying in the range of 600-900°C. The resulting ashes were characterised by a high percentage of phosphorus (30-170 g/kg ash), calcium (20-360 g/kg ash) and other valuable macro- and micronutrients like copper, iron, manganese and zinc. The ashes produced during the thermal treatment are safe in terms of sanitary and can be used as additives enriching the fertilisers and soil improvers.

Vermiculite as efficient sorbent of CeIII and CeIV

Environmental context Cerium, a Technology Critical Element with many technical, agricultural, and medicinal applications, is increasingly being discharged to the environment. One of the best ways to remove cerium from wastes is its fixation into inexpensive bulk material such as vermiculite. This paper investigates the mechanism of CeIII and CeIV uptake and capture by vermiculite in neutral and acidic aqueous solutions. Abstract This study focussed on the mechanism of CeIII and CeIV uptake on vermiculite (Ver), which has been studied sporadically. Chemical equilibrium and leaching experiments in acid solutions were evaluated using batch experiments and changes of mineral composition were monitored by X-ray powder diffraction analysis. The concentrations of Ce, Na, K, Ca, Mg, Al and Si were determined by atomic emission spectroscopy coupled with inductively coupled plasma (AES-ICP). The data for CeIII uptake on Ver in neutral aqueous solution were fitted both with adsorption and ion-exchange models. The latter, with a calculated selectivity constant =14.30 (L mmol–1)k–1, showed a better fit with experimental data than adsorption models. The uptake of CeIII on Ver at pH 2 was also controlled by intensive leaching of cations from 2:1 layers and therefore these data were not fitted. A much higher uptake of CeIV on Ver (~6 mequiv. g–1, i.e. ~210mgg–1) at pH 2 and 6 in comparison with the cation-exchange capacity of original vermiculite (1.28 mequiv. g–1) was found and explained. With regard to the different rate of CeIV species fixation on Ver, their different CeIV solubility in NaCl solution, aqueous acid solution (pH 2), and 3M H2SO4, three species of CeIV bonded on vermiculite are proposed. They are ion-exchanged CeIV, CeIV–complex 1 and CeIV–complex 2. The CeIV species uptake on Ver was quantitatively determined both for pH 2 and 6. The new findings show a very effective method of cerium uptake, especially from acidic aqueous solutions.

Bioleaching of hazardous waste

Landfill represents the least environmentally-friendly method of waste disposal because of possible pollution to the environment. Dangerous wastes pose the greatest problems and are often disposed of by combustion. This process reduces their volume but entails the formation of new types of dangerous waste. The present study focuses on the possibilities of the removal of the hazardous properties of waste originating from hazardous waste incinerators (three types of bottom ash and charcoal from flue gas cleaning) by bioleaching. Toxic pollutants originating from waste could be removed by bioleaching with Acidithiobacillus ferrooxidans. The effectiveness of bioleaching was evaluated on the basis of the pollutant content in the aqueous leachates. For studying the relation between the efficiency of bioleaching and the binding of pollutants in the waste, Tessier’s sequential extraction was used. A comparison of bioleaching efficiency and the results of sequential extraction shows that bioleaching can be used to remove elements which are in an exchangeable form or are bound to carbonates, meaning that they are bound in bio-available forms. Bacterial activity was also shown to change the bonds of pollutants in wastes, leading to increased solubility of the pollutant.

Adaptation of Acidithiobacillus bacteria to metallurgical wastes and its potential environmental risks

Metallurgical wastes – oxygen converter sludge, dust from cast iron production, lead matte, and slag from recycling of used lead batteries – were treated with Acidithiobacillus bacteria. Bacterial activity and adaptability on waste and some waste mixtures were investigated. Acidithiobacillus bacteria may easily attack oxygen converter sludge, lead matte and slag and affect the mobility of metals. Cast iron dust is not a suitable substrate for applied bacteria due to the absence of reduced sulfur and reduced iron in its mineralogical composition. Nevertheless, the pure culture was able to adapt to the mixture of this waste with slag. Disposal of these metallurgical wastes deserves special attention due to potential attack by microorganisms and consequent pH changes. According to subsequent release of hazardous substances to the environment, this phenomenon can lead to evident environmental risks.

Influence of Microwave Treatment on Ghassoul Stability

Moroccan clay with a significant portion of stevensite, locally known as Ghassoul, is a very good sorbent. For the facilitation of the sorbent separation, it is convenient to use its magnetically modified form. Recently, the composites of FexOy/Ghassoul have been prepared using simple microwave assisted synthesis and the effect of method preparation on composite composition has been proven. The aim of the presented work was to evaluate the effect of the microwave radiation on the structure and stability of native Ghassoul. Water extracts were prepared by batch method using deionized water. The leachate was prepared for 1, 6 and 24 hours in 1:1000 ratio of solid and liquid phase from the original material and the material after interaction with microwave radiation. In the filtrate, pH was determined as well as concentrations of Al, Ca, K, Mg, Na and Si using Atomic emission spectrometry with inductively coupled plasma. The results imply that microwave treatment of the material changes the pH of the leachates to more acidic compared to the original material in which the pH increases. Even the microwave treatment of Ghassoul did not cause changes in Al, in contrast with Si which was leached considerably more in the case of the microwave-treated sample. Opposite result was observed in the case of Na and Mg. Leached amounts of Ca were comparable in both the treatments, leached amounts K were not affected by the treatment and leaching time.

Effects of binder choice in converter and blast furnace sludge briquette preparation: Environmental and practical implications

Blast furnace and converter sludges are fine-grained waste materials characterized as dangerous waste with a negative impact on the environment. One way of recycling of such materials is briquetting followed by reuse of the material in the blast furnace. In the briquetting process, an important step is the choice of the binder suitable for manufacturing the briquettes with suitable mechanical properties. In this work, the effect of the binder choice (laundry starch UNIPRET, Portland cement) on the reduction of iron oxides in the assessed waste materials during thermal treatment (900, 1000, 1100 °C) is evaluated. Simultaneously, the effect of the binder choice on the amount and composition of the resulting waste gas was evaluated as well as its possible impact on the environment. The performed experiments proved the mutual relationship between the level of iron oxides to metal iron conversion, the binder content and retention temperature. Type of binder also affected the volume of the resulting waste gas. Factor analysis for mixed data (FAMD) proved that the resulting concentrations of the assessed hydrocarbons were correlated (apart from ethyne) and that they are closely associated with the binder applied. Conversely, the concentrations of ethyne, carbon monoxide and carbon dioxide were not associated with the binder but with the retention temperature. FAMD did not show any direct effect of final retention temperature on the amount of the rest of the resulting hydrocarbons. In comparison with the starch-containing briquettes, the cement-containing briquettes were also proved to lead to lower resulting concentrations of PAHs in the waste gas.

Microstructural Analysis and Magnetic Characterization of Native and Magnetically Modified Montmorillonite and Vermiculite

Two clay minerals of the similar 2 : 1 layer structure and chemical composition, vermiculite and montmorillonite, were studied using a wide spectrum of experimental methods in their original states and the magnetically modified states after mixing with microwave-synthesized iron oxide particles. This magnetic modification led to different microstructural morphology influencing magnetic behaviour at room and more pronounced at low temperatures.

Erratum to: Antimicrobial bionanocomposite–from precursors to the functional material in one simple step

In the published manuscript http://dx.doi.org/10.1007 /s11051-016-3664-y, the minimal inhibitory concentration (MIC) value for the monitored composites is incorrectly stated: 0.014 mg/ml is the stated value while the correct value is 0.14 mg/ml. The incorrect value does not influence the general concept of the article, its other results or its conclusions, nor it demands an in-depth revision of the published text. J Nanopart Res (2017) 19: 244 DOI 10.1007/s11051-017-3938-z

Leaching test for calcined kaolinite and kaolinite/TiO2 photoactive composite

Kaolinite is a suitable material for fixing TiO2 nanoparticles in a composite form. The kaolinite/TiO2 composite has promising photoactive properties which are as important as is the possible impact of the composite on the environment. Accordingly, the stability of the kaolinite/TiO2 composite dried at 105°C (KTI1) and calcined at 600 °C (KTI6) and the stability of the original kaolinite treated at various temperatures (105–800 °C) were studied by the leaching test in accordance with European standard BS EN 12457-2:2002 (British Standards Institution, 2002). The stability was evaluated on the basis of elements leached from the materials to extraction agents. Atomic emission spectrometry with inductively coupled plasma was used for determining the concentration of elements. In order to better understand the process of calcination and the structure changes in the kaolinite/TiO2 composite and calcined kaolinite, the materials were evaluated using X-ray powder diffraction and infrared spectroscopy with Fourier transformation. The processes of kaolinite dehydroxylation and metakaolinite formation were observed. Kaolinite is an appropriate carrier for composite preparation due to its stability even after its treatment at high temperatures. The experiments confirmed the TiO2 nanoparticles to be very strongly bound to the kaolinite surface. On the other hand, the experiments demonstrated that the presence of TiO2 on the kaolinite surface caused the release of Al in high concentrations to the final extracts, especially after kaolinite/TiO2 composite calcination.