Magnetic Properties Of The Particles From Beijing Steel Factory

Beijing Steel Factory (BSF) locates at the western Beijing city. It is a great steelenterprise being composed of coking plant, power plant, sintering plant, iron-sneting,rolling mill, steel-making plant. A mass of magnetic grains are released in theconveyance, stacking, disposing of the raw material and in the process of puddling,steel-making, steel rolling coal and the stacking of the steel residue. These grains willaffect the environment seriously when they enter into the soil nearby.In order to distinguish the magnetic grains from different production processesand their transport path, 58 samples of dust and raw materials were collected from thedifferent plants of the BSF. Moreover, 93 soil samples were collected from thezoology garden in BSF, Yongding River, Yingshan Forest Garden, virescence belt ofFushi Road near the BSF. These samples were from the dust in the surface, or topsoilwith a depth of 5cm. Among these samples, topsoil samples were collected fromvirescence section of Fushi Road, and two sections of Yongding River bank.Environmental magnetic parameters were measured for all these samples.Through measuring the magnetic parameters of representative samples, such assusceptibility, frequency-dependent susceptibility ( χfd ) , anhysteretic remnantmagnetization(ARM), temperature dependence of magnetic susceptibility (κ-T curve),isothermal remnant magnetization(IRM) and reversal demagnetization curve,hysteresis loop, it can be concluded that:1. Magnetic minerals in dust samples and raw material samples of BSF aredominated by magnetite, with minor paramagnetic and antiferromagnetic minerals.There is a lot of hematite in sintering minerals. The magnetic domain offerrimagnetism grain is pseudo-single-domain or multidomain;extract mineralpowder, sintering ore, minute break ores and all dust samples are characterized ofhigh susceptibility (>10-5m3/kg) and low frequency-dependent susceptibility(<3%).There are certain differences in magnetic parameters among the magnetic grains fromdifferent production process. But we can not distinguish them using magnetic methodalone.2. The soils around BSF area were affected by the magnetic grains that camefrom BSF.3. The magnetic mineral of samples from around BSF is magnetite, and the grainsare mainly pseudo-single-domain or multidomain. The facts that the longer distancefrom BSF, the lower value of mass susceptibility, the higher value of frequency-dependent susceptibility and remanence coercivity force, indicate that the magneticgrains are from BSF, and that the amount of magnetic grain is becoming fewer withthe distance from the factory, grains becoming smaller.