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1

Study of the effect of airflow rate and agitation speed on entrainment of ash particles in bottom ash flotation

Kim Minsik, You Kwangsuk, Kim Kwanho, Jeon Yong-woo

Physicochemical Problems of Mineral Processing

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2024

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Vol. 60, iss. 2

art. no. 187835

EN

To enhance the recovery and grade of the final product, reducing the entrainment of the hydrophilic particles during flotation is critical. We conducted the improvement of entrainment to reduce the amount of ash in the concentrate with the purpose of recovering high-quality unburned carbon from the bottom ash and reusing it as fuel in power plant. In this study, we investigated the effects of airflow rate and agitation speed on the entrainment of hydrophilic particles. In the selfaerating flotation machine, it was difficult to independently control the agitation speed and airflow rate, resulting in the degree of entrainment of 0.74. By independently controlling the airflow in which hydrophobic particles can float under conditions of the degree of entrainment with 0.7 (low agitation speed: 900 rpm), the combustible recovery and unburned carbon content of concentrate were 93.71% and 93.60%, respectively. The degree of entrainment was found to be 0.57, and entrainment could be minimized through independent control of airflow rate and agitation speed. To minimize entrainment, it is effective to inject air that can suspend hydrophobic particles in a low agitation speed condition.

2

Selection of the best route for column configuration in an existing copper circuit

Can N. Metin, Altun Okan

Physicochemical Problems of Mineral Processing

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2019

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Vol. 55, iss. 2

552--564

EN

This study was aimed to utilize column flotation to obtain much cleaner concentrate in the Cu circuit. However, the numbers of equipment and the proper streams for column application should be the key for successful operation. Therefore, the effects of some operational parameters such as wash water rate, airflow rate and froth height were investigated on the streams of namely Cu first cleaner concentrate, Cu rougher concentrate and Cu third cleaner concentrate in terms of mineral recoveries and selectivity. Distribution of wash water rate to products was also determined by a tracer test method. Optimum operating conditions and accordingly performance of the column were determined by simulation studies. According to the results, the suitable streams for industrial scale flotation column are advised as the rougher concentrate and/or first cleaner concentrate. With series installation of columns, it is possible to obtain two different concentrates which include 22% Cu, 4% Zn and 17% Cu, 8% Zn without any decrease in overall recovery of plant.

3

Emisja amoniaku i dwutlenku węgla z obór przeznaczonych dla krów mlecznych

Mazur K.

Problemy Inżynierii Rolniczej

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2012

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R. 20, nr 4

141--150

PL

W pracy przedstawiono wyniki pomiarów emisji amoniaku i dwutlenku węgla z sześciu obór dla krów mlecznych, w tym dwóch boksowych ściółkowych, dwóch na głębokiej ściółce, jednej z podłożem samospławialnym oraz jednej boksowej bezściółkowej, zlokalizowanych na terenie województw lubelskiego, mazowieckiego i podlaskiego. Badania prowadzono w okresach letnim i zimowym. Wentylacja w oborach była naturalna (przez szczelinę kalenicową), w związku z tym emisję szkodliwych gazów z obór badano metodami bilansowymi (bilans dwutlenku węgla oraz wilgotności). W celu obliczenia wskaźnika przepływu powietrza zbadano: stężenie dwutlenku węgla, amoniaku oraz temperaturę i wilgotność względną powietrza wewnątrz i na zewnątrz obór. Mierzono poziom emisji gazów w ciągu doby. Średnia dobowa emisja amoniaku wahała się od 0,51 do 2,64 g·h-1·DJP-1, natomiast dwutlenku węgla od 223,9 do 962,6 g·h-1·DJP-1, w zależności od systemu utrzymania i pory roku. Największą emisję amoniaku latem (2,64 g·h-1·DJP-1) stwierdzono w oborze boksowej z płytką ściółką, z najmniejszą obsadą. Obora boksowa, bezściółkowa była budynkiem, w którym odnotowano największą emisję amoniaku zimą oraz drugą pod względem wielkości emisję amoniaku i dwutlenku węgla latem. Emisja amoniaku zimą w tej oborze wynosiła 1,47 g·h-1·DJP-1, natomiast emisja CO2 latem - 585,76 g·h-1·DJP-1.

EN

The scope of research dealt with the emissions of ammonia and carbon dioxide in six dairy cattle barns: two with littered boxes, two on the deep litter, one with self-flushing floor and one with the litterless boxes. The objects tested were located in Lubelskie, Mazowieckie and Podlaskie provinces. Investigations were conducted during summer and winter seasons. All buildings were equipped with natural ventilation (through the roof ridge gap). Gaseous emissions from the cattle barns were determined by using balance methods (balance of carbon dioxide and air humidity). In order to calculate the ventilation rate, carbon dioxide and ammonia concentrations were measured, as well as the temperature and relative humidity of air inside and outside of the cattle barn buildings. The rates of gaseous emissions were measured over 24 hrs. Average ammonia emission (per 24 hrs) ranged within 0.51-2.64 g·h-1 LU, whereas the carbon dioxide within 223.9-962.6 g·h-1 LU, depending on the housing system and season of year. The highest ammonia emission in summer (2.64 g·h-1 LU) took place in the cattle barn with shallow-littered boxes and the smallest livestock density. The cattle barn with litterless boxes was characterized by highest ammonia emission in winter; it also took a second place in respect of both, ammonia and carbon dioxide emissions in the summer. Ammonia emission in this cattle barn in winter amounted to 1.47 g·h-1 LU, whereas CO2 emission in the summer - 585.76 g·h-1 LU.

4

Remediation of soils contaminated with trichloroethylene

Albergaria J. T., Alvim-Ferraz M. C. M., Delerue-Matos C. M.

Environmental Biotechnology

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2010

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Vol. 6, No. 2

37-41

EN

Soil contamination is a common problem in our society. Several activities introduce contaminants in soils affecting their quality and future utilization. In order to invert this situation and to avoid further spreading of the contaminant several remediation technologies could be used. For soils contaminated with trichloroethylene (TCE), Soil Vapor Extraction (SVE) can be an efficient remediation technology. It involves the application of vacuum to the soil matrix creating an airflow that conduce the volatized contaminant to extraction wells that lead them to the exterior of the soil where they are properly treated. This work presents the results obtained in the soil vapor experiments performed in a laboratory using soils with different water contents contaminated with TCE. These experiments aimed the study of the influence of soil water content and the airflow used in the remediation time and on the process efficiency. The results showed that in sandy soils contaminated with TCE: a) for similar levels of contamination, the increase of the soil water content from 0 to 4% created an increase of the concentration of TCE in the gas phase of the soil, in some cases by almost 50%; b) the influence of water content is not significant being overlapped by influence of the airflow rate; c) SVE performed with higher airflow rates had shorter remediation times (in some cases four times shorter) without any significant impact on the process efficiencies (fluctuations of 1 to 3%); and d) for the experimented soils, the utilization of higher airflow rates led to shorter and consequently cheaper remediation.