environment impact evaluation of a new type continuous mixing

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Inlet 2(2 1 )layersOutlet Inlet 4(2 2 )layersOutlet Inlet 8(2 3 )Outlet layersnn unitsMY-mixer2 nlayersVerticalInletHorizontaloutletFlowof MaterialsKneadingProcessLappingProcessFig.3 Continuous concrete mixer “MY-mixer” and its mixing theory.and continuous mixing plant are estimated anddiscussed. In these estimations, electricityconsumption and CO 2 discharge are calculated asenvironmental impacts. First the total electric powerof each equipment, namely necessary power per hour(kW) for operating the plant, is calculated. And thencalculated power divided by production capacity ofthe plant is power consumption per unit volume ofproduct (kWh/m 3 ), and the power consumptionmultiplied by environmental impact rate of CO 2(kg/kWh) is CO 2 discharge per unit volume ofproduct (kg/m 3 ). In these calculations, the requiredpower for each equipment is referred to reference 6.And environmental impact rate of CO 2 is defined as0.371kg/kWh referred to the investigating result byconcrete committee of Japan society of civilengineers (Reference 1).4. ESTIMATION RESULTS4.1 Concrete plantFig.4 shows the outline of batch mixing plant.This plant equips 2m 3 pug mill type forced mixer.Since it is necessary to mix dam concrete composedof large size particle of aggregate, the cycle time ofmixing is set to 90 minutes, and thus its mixingcapacity is 80m 3 per hour. On its manufactureprocesses, first the materials are transported to themain tower of plant by each feeder and beltconveyers, and then measuring of materials andmixing of concrete are conducted repeatedly. Fig.6shows the outline of continues mixing plant. Thisplant equips a continuous mortar mixer and acontinuous concrete mixer “MY-mixer”. Thecapacity of continues mortar mixer is 70m 3 /h and thecapacity of MY-mixer is 150m 3 /h. In its manufactureprocesses, first the course aggregate are fed to thebelt conveyer 1 by each feeder continuously. At thesame time, powder materials, fine aggregate andwater are fed into continuous mortar mixer andmixed continuously, and then the mixed mortal is fedon the course aggregate on belt conveyer 1. And theall of materials on belt conveyer 1 are transported tothe top of the MY-mixer and dropped into the insideof MY-mixer, and then concrete mixing is conductedcontinuously at the inside of MY-mixer only bygravity force. The details of structure andequipments of their two plants are given in table 1.
Mixing plant(Pug mill mixer)CementFryashSand and gravelG1 G2 G3 SBelt conveyer 2Belt conveyer 1WaterFig.4 Outline of batch mixing plant for concrete.CementGravelG2G1FryashG3SMortar mixerGravelWaterMortarBelt conveyer 2Belt conveyer 1Mortar and GravelMY-mixerFig.5 Outline of continuous mixing plant for concrete.Table 1 Capacity and equipments of plant.Batch mixing plant Continues mixing plantMaximum production capacity 80 m 3 /h 150 m 3 /hEquipment for material suppliment belt conveyer-1 350t/h belt conveyer-1 350t/hbelt conveyer-2 180t/h belt conveyer-2 180t/hcement feeder 12t/h belt feeder 120t/h 4water pomp 0.5m 3 /mindust extractor 20m 3 /mincement feeder 12t/hwater pomp 0.5m 3 /mindust extractor 20m 3 /minMixermixer 2.0m 3 Continues mortar mixer 70m 3 /hMY-static mixer 650*650 L=6.5mNotesmixing cycle time 90s
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Page 7 and 8: CementMixing plant(Dram type mixer)

environment impact evaluation of a new type continuous mixing

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