Solidfication and reuse of coal fly ash by heating-compressive method

在第一年的这项研究中，粉煤灰与一些添加剂通过热压法固化，反应温度为100 - 250 ℃，抗压强度为0 - 10 MPa。将灰和硅灰或矿渣粉末（5 - 20重量%）与NaOH溶液（粉末重量的15%）充分捏合以制备起始材料。将混合粉末放入内径为20 mm的圆柱形高压釜中，由于高压釜的填料收缩，在5 MPa下压缩。然后用油泵在一定压力下用油缸连续压缩，加热到预定温度，用抗压强度和抗拉强度评价固化体，用重量和60 ℃干燥后的表观体积测定固化体的密度，并对原料中的主要元素进行静态浸出试验，得到以下结果：在s的情况下 关于我们 硅灰作为添加剂，抗压强度随硅灰含量的增加而增加。在140 ℃、4 MPa、掺量为10%的条件下固化时，粉煤灰混凝土的抗压强度比普通粉煤灰混凝土高得多，而密度比普通粉煤灰混凝土低得多。试验结果表明，固体中主要元素的浸出量对抗压强度有影响，以矿渣为添加剂，在230 ℃、10 MPa的固相条件下，加入粒度较小的矿渣粉，固体的抗压强度可达64.3 MPa（8000 cm ~ 2/g），且在此条件下得到的实心体抗压强度比普通粉煤灰混凝土高一倍以上，抗拉强度与普通粉煤灰混凝土相当，密度比普通粉煤灰混凝土低。用比第一年更大的设备生产具有大直径（50 mm）的实心体。固体的条件由较小固体的结果来考虑。特别是非JIS粉煤灰，这是更多的问题，处置，在本研究中使用。为了证实粉煤灰的长期使用性，用特氟龙高压釜在100 - 200 ℃的高温下对粉煤灰进行了改性试验。根据去年的结果，起始材料在150 - 250 ℃的温度下固化，在10 MPa下压缩，并使用表面积为8000 cm 2/1g重量的矿渣。（1）在250 ℃的反应温度下，获得了具有50 MPa的高抗压强度和1.80的轻质密度的固体。（2）随着矿渣微粉掺量的增加，实心体的抗压强度增加。当掺量达到10%时，抗压强度得到极大的提高。从经济性和强度来看。建议矿渣粉的最佳掺量为20%。（3）当反应温度为225 ℃时，随着反应温度的升高，材料的抗拉强度提高了2.9MPa，抗拉强度/抗压强度比为1/20。该值远小于普通混凝土砌块。（4）粉煤灰在碱（NaOH）溶液中的改性在反应温度为150 ℃和反应时间为30分钟的条件下产生了一些合成沸石。少

In this study of the first year, coal fly ash with some additives was solidified by a heat-compressive method at reaction temperatures of 100 - 250 degree C and at compressive strengths of 0 - 10 MPa. The ash and silica fume or the slag powder 5 -20 wt%) was kneaded well with NaOH solution (15% of powder weight) to prepare the starting material. The mixed powder was put into the autoclave, which has a cylindrical shape with a 20 mm of inner diameter, and compressed at 5 MPa because of the constriction of the packing of the autoclave. Then it was continuously compressed at the certain pressure with an oil cylinder by oil pump and was heated to a planned temperature.The solidified bodies were evaluated by the compressive strength and the tensile strength.Density of the solidified body was measured from its weight and apparent volume after drying at 60 dgree C.And static leach tests for main elements of starting material were performed.The following results were obtained ;In the case of s … More ilica fume as additive, the compressive strength was increased with the content. When the starting materials was solidified at 140 degree C, at 4 MPa, and the content of 10%, the compressive strength was much higher and the density was lower than that ordinary fly ash concrete. The results of leaching tests suggested that the leached amount of main elements for solid body affects the compressive strength.In the case of the slag as additive, the compressive strength of the solid body reached 64.3 MPa, when solid conditions were at 230 degree C at 10 MPa, and addition of the slag powder with smaller particle (8000cm2/g), And the solid body by above conditions has higher of twice compressive strength, same level of the tensile strength, and lower density than that of ordinary fly ash concrete.In the study of second year, the solid bodies with large diameter (50 mm) were produced with larger equipment than the first year. The conditions for solid were considered by results for smaller solid bodies. Especially non- JIS fly ash, which is more problem about the disposal, was used in this study. An alteration test under the elevated temperature at 100 - 200 degree C for the fly ash was performed with an Teflon autoclave in order to confirm the long period working. From results of last year, the starting material was solidified the tenperature at 150 - 250 degree C, the compression at 10 MPa, and using the slag with the surface area of 8000cm2 per 1g weight.The following results were obtained ;(1)The solid body with a high compressive strength of 50 MPa and a light density of 1.80 was obtained under the reaction temperature of 250 degree C.(2)The compressive strength of solid body was increased with the content of slag powder. When the content of 10% reached, the compressive strength was extremely increased. From economical and the strength view points. it suggested that the optimum content of slag powder is 20%.(3)The tensile strength was increased about 2.9 MPa with the increasing of reaction temperature up to 225 degree C.And the ratio of tensile strength / compressive strength showed 1/20. The value is much smaller than that of normal concrete block.(4)The alteration of the coal fly ash in alkaline (NaOH) solution produced some synthesis zeolites under conditions at the reaction temperature of 150 degree C and for the reaction time of 30 minutes. Less