發(fā)布時(shí)間：2018-03-06 06:09

  本文選題：赤泥　切入點(diǎn)：活化　出處：《中北大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：赤泥是生產(chǎn)氧化鋁時(shí)所排出的固體廢棄物，排放量大，因其堿含量高、活性低，難以有效利用。目前主要的處置方式是露天堆存，會(huì)占用大量土地、引起地下水和空氣污染，亟待處理。 本論文針對(duì)拜耳法赤泥含堿量高，用在建筑材料中會(huì)引起堿集料反應(yīng)、泛白的問(wèn)題，利用XRD、火焰光度計(jì)等檢測(cè)手段研究了堿在赤泥中的存在形式（可溶堿、非可溶堿）及比例。同時(shí)以堿溶出率、凈漿強(qiáng)度為控制目標(biāo)，研究了赤泥在活化（熱活化及加鈣熱活化）過(guò)程中可溶堿和不可溶堿的變化規(guī)律及其對(duì)赤泥活性的影響。利用物相耦合原理，研究了利用粉煤灰高溫吸收赤泥可溶堿降低赤泥可溶堿新技術(shù)，并在系統(tǒng)研究粉煤灰摻量、細(xì)度、養(yǎng)護(hù)時(shí)間對(duì)粉煤灰固結(jié)赤泥可溶堿效果影響的基礎(chǔ)上，研究了粉煤灰固堿機(jī)理。主要結(jié)論如下： （1）拜耳法赤泥中的堿主要分為兩部分：一部分是可溶性堿，是在溶出鋁土礦過(guò)程中帶入的附著堿液，一部分是不可溶性堿，是鋁土礦中的SiO2與鋁酸鈉溶液反應(yīng)生成的不溶性水合鋁硅酸鈉，主要以鈣霞石的形式存在。其中赤泥中可溶堿含量占總堿量的54%，非可溶堿占總堿量的46%。 （2）在赤泥活化過(guò)程中，其可溶堿含量隨溫度的升高先升高后降低，在700℃時(shí)達(dá)到最大值，表明此時(shí)水合鋁硅酸鈉的結(jié)合度低，離子溶出率大，故活性較高。在煅燒溫度升高的過(guò)程中，赤泥中的一些含水礦物在500℃之前分解，并且鈣霞石的衍射峰強(qiáng)度開(kāi)始降低，所以可溶堿含量逐漸增大，在800℃開(kāi)始出現(xiàn)結(jié)構(gòu)穩(wěn)定的鈣鋁黃長(zhǎng)石和鈉鋁黃長(zhǎng)石，Na2O被固結(jié)在穩(wěn)定的鈉鋁黃長(zhǎng)石中，所以可溶堿含量有所降低，900℃時(shí)結(jié)晶度進(jìn)一步增大，更多活性物質(zhì)被固結(jié)，離子溶出率減少，故可溶堿含量進(jìn)一步降低。不同溫度下可溶堿含量的變化與凈漿試塊的早期強(qiáng)度變化一致，但隨著齡期的增長(zhǎng)，在900℃以下時(shí)，試樣的抗壓強(qiáng)度逐步增長(zhǎng)，在900℃出現(xiàn)下降。并且在煅燒過(guò)程中，赤泥中的堿含量隨著溫度的升高而有所揮發(fā)，，800℃之前揮發(fā)量較大，800℃之后，Na2O被固結(jié)，揮發(fā)量減小。 （3）赤泥中加入不同比例的石灰并在1200℃下煅燒，生成具有水化活性的C2S及可溶出的鋁酸鈉，提高了赤泥的活性，最高堿溶出率可達(dá)82.55%。在低齡期時(shí)，凈漿試塊的強(qiáng)度與堿的溶出率一致，但齡期增長(zhǎng)后，C2S水化程度增大，提高了凈漿試塊的強(qiáng)度。 （4）利用粉煤灰在高溫養(yǎng)護(hù)下與赤泥作用可以降低可溶堿的含量。赤泥與粉煤灰比例為1:2.5時(shí)，赤泥的堿溶出率最低；粉煤灰細(xì)度越大，赤泥可溶堿的含量越低；隨著養(yǎng)護(hù)時(shí)間的增加，粉煤灰-赤泥材料中的可溶堿含量降低。經(jīng)XRD檢測(cè)可知，鈉與粉煤灰溶出的Al2O3、SiO2反應(yīng)生成了不溶的鈉系菱沸石。
[Abstract]:Red mud is a solid waste discharged from the production of alumina. It has a large amount of discharge, because of its high alkali content and low activity, it is difficult to be effectively utilized. At present, the main disposal method is open storage, which will occupy a large amount of land and cause groundwater and air pollution. There is a great deal to be done. Aiming at the problem of high alkali content in Bayer red mud, which can cause alkali aggregate reaction and widespread whitening in building materials, the existing forms of alkali in red mud were studied by means of XRD, flame photometer, etc. Insoluble alkali) and proportion. At the same time, with alkali dissolution rate, pulp strength as the control target, The changes of soluble and insoluble alkali and their effects on the activity of red mud during the process of activation (thermal activation and thermal activation with calcium) were studied. The new technology of reducing the soluble alkali of red mud by high temperature absorption of red mud by fly ash was studied, and the effects of fly ash content, fineness and curing time on the effect of soluble alkali of fly ash consolidation red mud were studied systematically. The alkali-solid mechanism of fly ash is studied. The main conclusions are as follows:. 1) the alkali in Bayer red mud is mainly divided into two parts: one is soluble alkali, the other is the attached lye brought in during the dissolution of bauxite, and the other is insoluble alkali. It is an insoluble sodium aluminosilicate formed by the reaction of SiO2 in bauxite with sodium aluminate solution, mainly in the form of calcium nepheline. The soluble alkali content in red mud accounts for 54% of the total alkali content, and the non-soluble alkali content accounts for 46% of the total alkali content. (2) during the activation of red mud, the soluble alkali content increased first and then decreased with the increase of temperature, and reached the maximum value at 700 鈩

本文編號(hào)：1573635