The application of magnetic carriers in wastewater treatment

Ferromagnetic fluid is a kind of polyphase liquid, which is a stable colloid system of sufficiently small mono-domain magnetic particles covered by a film of surfactant and dispersed in a base liquid. Ferrofluids can be prepared in various base liquids such as water, hydrocarbons, mercury, etc., according to them utilisation. The basic properties of ferrofluids, i.e. the high magnetic polarisation of saturation and zero remanence predestine their application in various industrial branches including mineral processing and wastewater treatment.Wastewater treatment by the application of ferrofluids under magnetic field resides in the action of the field on the ferrofluid added to the oil substance. Strongly magnetically polarisable fluids enable to increase the magnetic susceptibility of oil substances to suitable level for their removal from water by a magnetic way. It was observed that the oil drop with the weight of 3.10 -3g and the ferrofluid concentration of 3% starts to move in the direction of the magnetic intensity growth at the minimal value of 105 A.m-1. It means that ordinary permanent magnet with the magnetic induction of 0.1 T causes the movement of the oil drops with a relatively small admixture of ferrofluid on the water level. This knowledge is very important for the design of magnetic filtration device which will be able to separate oil substances from water.Modification of magnetic properties of weakly magnetic materials by ferrofluids was also carried out in the case of magnetic filtration of water contaminated by fine grains of copper concentrate created by chalcopyrite. After admixing the ferrofluid into the suspension the recovery of mineral to the magnetic filter product ranges from 75 % to 98 % depending on the kind of ferrofluid and pH values. It was observed that in the case of water-based ferrofluid the recovery decreases with the increasing of pH value. But, on the other hand the increasing of pH value under the application of kerosene-based ferrofluid results in the increasing recovery. According to the obtained recovery values, ferrofluids can be consider a good agent for the magnetic susceptibility modification.The magnetic sorbents consisting of magnetite seed covered by the film of K4Fe(CN)6 were applied in the treatment of water polluted by copper ions. The magnetic sorbent was added in the solution during intensive mixing in the amount of 25g per Litre of contaminated water. The Cu concentration of 48.2 µg.ml-1 decreased to the value of 3.7 µg.ml-1 after magnetic filtration.Generally, a method for separating particles of a nonmagnetic material from an aqueous mixture comprising the steps of: rendering the surfaces of said particles magnetic by contacting them with a magnetising reagent comprising water containing particles of a magnetic material. Each of said magnetic particles has a two layer surfactant coating including an inner layer and an outer layer, said inner layer covering said magnetic particle and being a monomolecular layer of a first water soluble, organic, heteropolar surfactant containing at least 3 carbon atoms and having a functional group on one end which forms a bond with said magnetic particle and a hydrophobic end, and said outer layer coating said inner layer and being monomolecular layer of a second water soluble, organic, heteropolar surfactant containing at least 3 carbon atoms and having a hydrophobic end which is bonded to the hydrophobic end of said first surfactant and a functional group on the other end capable of bonding with said nonmagnetic particles; and subjecting the mixture to a magnetic separation to cause said magnetised particles to be separated therefrom

Glassceramics from Industrial Waste Prepared in a Microwave Furnace

This work presents the study of glassceramics from nickel leaching residue used as a heavy metal carrier (Cd, Pb) preparedby microwave vitrification. The Vicker`s microhardness, chemical durability and magnetic susceptibility of vitrified waste was tested.The glassceramics containing 40-50 % of nickel leaching residue with a high microhardness and very good chemical durability wasobtained in a short time of heating (45 minutes)

The influence of microwave radiation on the failure of rocks

The heating and processing of materials using microwaves becomes increasingly popular for industrial applications. Compared to conventional heating, microwave processing can provide a rapid, the production of materials with unique properties, and reductions in manufacturing costs and processing times.The positive influence of the microwave radiation on the faulting of the individual rocks is described. At the heating of the heterogeneous ores, the microwaves have an selective effect for individual mineral components. Owing to the different degree of to heating and thermal dilatation the stress and destructive attendants arise, which increase the faulting of rocks. The rate of the faulting has been investigated on the basis of measurement of the elastic waves motion velocity by the impulse-dynamic method.On the basis of the measured values of elastic wave motion in the observed rocks before and after their microwave heating the coefficient of faulting was computed according to the relation (1). Subsequently, from these coefficients the rate of faulting was determined for individual rocks according to Jaeger (Table 1).Various rate of rocks faulting caused by the radiation depend on their ability to absorb microwave power. High rate of faulting was observed in rocks with strong absorption of microwave power unlike from substances which weakly absorb the radiation. Particularly, a high rate of faulting after microwave heating was observed at samples of limestone (Roòava-Jovice) and magnesite (Haèava). Low rate of faulting was obtained in the case of granodiorite (Podhradová), granite (Hnilec), sandstone (Horelica), marble (Koelga) and andesite (Huboovce).The influence of microwave energy on the rate of rocks faulting was confirmed. The new knowledge can be applied for the intensification of the rock disintegration processes

Preparation of briquettes on the basis of desintegrated phyto-materials and the admixture of fine-grained coal and coke

The contribution deals with the preparation of small-diameter briquettes on the basis of desintegrated phyto-materials and the admixture of coal and coke. The phyto-materials are classified as a dry biomass that can be, on the one hand, the wastes from wood-working industry,(sawdust, chips, bark, etc.) or dried mass from the plant production and, on the other hand, the mass of quick-growing plants cultivated on special plantations. In present time this renewable energy resource attracts attention by its heating value ranging from 10 to 16 MJ.kg-1 (EkoWATT, 2001), a low ash content of 0.5 6.5 % and by a low sulphur content in a water free sample of 0.05 0.12 %.As a phyto-material the spruce sawdusts having a grain size of 2 mm were used. The admixture of brown coal, hard coal and coke with a grain size of 0.040 mm was added to the sawdust and in such way prepared mixtures were subjected to briquetting with the aim to obtain small-diameter briquettes. The influence of admixtures amount on the density, and the suitable briquetting press have been studied. A saleability of briquettes on the basis of phyto-materials is conditioned by their density that must be higher than 1,000 kg.m-3. Thus, an adding of denser material with a relatively high calorific value would enable to attain the required density as well as to retain and/or to improve the main utility properties, i.e. calorific value and ash content.The adding evinces itself in an enhancement of briquetting press, but also density of obtained briquettes is often much higher that required by the market. It was showed that in the case of clear spruce sawdust the density of 1,059 kg.m-3 under the briquetting press of 250 MPa can be attained. According to other results, an admixture of brown coal is not very favourable because briquetting press exceeds the value of 300 MPa. As to hard coal adding, the presses under 250 MPa were achieved at the content of 25 30 %. The density of these briquettes ranges from 1,050 1,085 kg.m-3. The best results have been obtained by adding coke. The briquetting press lower than 250 MPa has already been attained at the coke content of 15 %. The further increase of the coke content up to 30 % resulted in the briquetting press of 185 MPa. The density of briquettes with the admixture of coke was from 1,037 to 1,063 kg.m-3

Utilization of ferrofluids in coal preparation

The contribution deals with the possibilities of ferrofluid application as a separation medium and a selective wetting agent with the aim of desulphurization and ash content decreasing of brown coal from Slovak deposits. The influence of magnetic field induction on sulphur and ash content in the products of magneto-hydrostatic separation was observed. The adsorption of ferrofluids on the surface of coal was observed. The ferrofluids cause above all the change of magnetic properties and they increase the separability of materials under magnetic field

Possibility of Modification of Zeolites by Iron Oxides and its Utilization for Removal of Pb(II) from Water Solutions

Ion-exchange properties of cations from lattice and ions from solutions are characteristic for zeolites. Zeolites as sorbents are used in many branches of industry. Ion-exchange reactions of cations on zeolites have been a theme of many works. With the exception of using natural zeolites as the sorbent, a modification of surface of zeolites and preparation of synthetic zeolites has received interest lately. One of the common modification of zeolites is modification by iron oxides, which increases capacity of adsorption. In this work, we prepared a modified zeolite by the precipitation of magnetite on the surface of zeolite. This new adsorbent was used to remove of Pb(II) from waste water. The maximum adsorption capacity was 73,25 mg/g from the solution of Pb with the concentration of 400 mg/l

Application of the multigravity separator Mozley in the preparation of steam coal from the Cíge¾ Colliery

The contribution presents the results of tests on a gravity separation of steam coal from the Cíge¾ Colliery. The preparation tests were carried out in a multigravity separator Mozley. The preparation conditions and the quality of obtained products are summarized in tables. The introduced results such as the ash content in washed coal (from 44 to 57%) and an ash recovery into reject (from 5 to 12%) point to the fact that the application of the Mozley separator is not advisable for the steam coal preparation from the Cíge¾ Colliery

Application of the Matrix Model of Hydrocyclone in Coal Preparation

The paper describes mathematical model of the water only cyclone function on the basis Of experimental data. The experiments have been realized in a pilot plant cyclone. The model was verified in the case of steam coal preparation from the Cíge¾, Handlová and Nováky localities. The obtained results confirmed that the applied model is suitable for the design of cyclones parameters under the operating condition