WO2018023918A1 - 一种用作造纸填料的粉煤灰表面沉淀结晶式包覆改性的方法 - Google Patents

一种用作造纸填料的粉煤灰表面沉淀结晶式包覆改性的方法 Download PDF

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WO2018023918A1
WO2018023918A1 PCT/CN2016/110208 CN2016110208W WO2018023918A1 WO 2018023918 A1 WO2018023918 A1 WO 2018023918A1 CN 2016110208 W CN2016110208 W CN 2016110208W WO 2018023918 A1 WO2018023918 A1 WO 2018023918A1
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fly ash
reaction
concentration
gas
modifying
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PCT/CN2016/110208
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樊慧明
齐亚楠
刘建安
李哲
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华南理工大学
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/63—Inorganic compounds
    • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/63—Inorganic compounds
    • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
    • D21H17/69—Water-insoluble compounds, e.g. fillers, pigments modified, e.g. by association with other compositions prior to incorporation in the pulp or paper
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/63—Inorganic compounds
    • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
    • D21H17/675—Oxides, hydroxides or carbonates

Definitions

  • the invention belongs to the technical field of filler modification in the discipline of pulp and paper engineering, and particularly relates to a method for precipitating crystalline coating modification of fly ash surface used as papermaking filler.
  • fly ash is one of the largest sources of municipal solid waste emissions in China.
  • the stacking of fly ash will directly or indirectly cause a series of environmental problems such as the atmosphere, soil and river, and cause great waste of resources.
  • domestic and foreign researchers have studied the resource utilization technology of fly ash through various methods, and made breakthroughs in many aspects such as construction, roads, sewage treatment, mineral extraction, and material filling and filling.
  • the use of these fields has a series of problems such as low product yield, low added value, and high processing cost.
  • fly ash has a chemical composition similar to that of kaolin used in the paper industry and a unique surface pore structure, it can be used for paper filling.
  • the interference of non-burning carbon and iron oxides in the fly ash particles makes the whiteness only about 30% ISO, which is difficult to meet the requirements of high whiteness paper filling ( ⁇ 80% ISO) in papermaking filler. The application of the field is therefore limited.
  • Gai Guosheng proposed a method of mixing fly ash with Ca(OH)2 at 40 ⁇ 100oC, then neutralizing with CO2 under cooling to normal temperature, then filtering and drying the slurry. It is mainly modified by the change of surface structure of fly ash under high temperature alkaline condition. The later CO2 only plays a supporting role in neutralizing excess Ca(OH)2. Yu Xiaodong disclosed another method for decolorizing fly ash: firstly soak the fly ash with carbon content of 0.1% ⁇ 1% into water and heat it to boiling, then pass through 200oC high temperature CO2 gas for 5 ⁇ 15min. The whiteness can be increased to 70-81% ISO. This method is constrained in the application of high carbon content whitening and needs to provide a certain high temperature environment.
  • the present inventors have also disclosed a method of first-time high-temperature carbon removal and starch-adhesive bonding of PCC (precipitated calcium carbonate) particles to the surface of fly ash particles, which is a slightly complicated process and requires energy consumption.
  • PCC precipitated calcium carbonate
  • the present invention proposes a novel fly ash surface precipitation crystal coating modification method.
  • the original particle structure of the coal ash is not destroyed.
  • the inventive scheme is as follows.
  • a method for precipitating crystalline coating modification of fly ash surface used as papermaking filler comprising the following methods:
  • Crystallization coating uniformly mixing the selected mixed suspension of fly ash and Ca(OH) 2 solution at normal temperature, and then introducing CO 2 gas by bubbling from the bottom of the reaction vessel under stirring. Precipitation crystallization reaction occurs, after the reaction, the introduction of CO 2 gas is stopped and the reaction is terminated by stirring;
  • Concentration reserve The concentration of the mixed solution after the reaction is adjusted with water, and then used as a papermaking filler.
  • the carbonization reaction at a normal temperature (10 to 30 ° C) is used to realize the calcium carbonate precipitation crystal coating modification on the surface of the fly ash, and no other pretreatment method or physical and chemical reaction under high temperature conditions is used.
  • the mass ratio of the solute Ca(OH) 2 in the fly ash to the Ca(OH) 2 solution is 0.1 to 3.0; and the mass percentage concentration of the fly ash in the mixed suspension is 20% to 50 %.
  • the coating modified reaction medium used is a Ca(OH) 2 solution, and CO 2 is introduced to produce precipitated crystals on the surface of the fly ash, and no other chemicals are added.
  • a gas dispersing device which is continuously bubbled at the bottom of the reaction vessel is used, and the gas dispersing device is an aeration plate of a single intake port.
  • the stirring rate control range is 100-600 rpm
  • the CO 2 flow rate is controlled at 0.1-1.5 L/min
  • the reaction time is 10-60 min.
  • the fly ash obtained after the completion of the reaction - The calcium carbonate complex suspension is directly adjusted for concentration and used for paper filling.
  • the adjusted mass percentage is 1% ⁇ 30%.
  • the raw materials (fly ash, Ca(OH) 2 and CO 2 ) are convenient to obtain, the cost is low, and the reaction can occur under the condition of normal temperature of 10 ⁇ 30oC, which is suitable for different environments;
  • the whiteness performance of the final product can be controlled by the reaction conditions, and the whiteness control range is 65 ⁇ 86% ISO, which can meet the requirements of filling and filling paper with different whiteness requirements.
  • the concentration is directly adjusted to 1% ⁇ 30% and sent to the pulping system of the paper machine. It is not necessary to add it after drying, which effectively reduces energy consumption.
  • This technology provides a high value-added utilization of fly ash solid waste and provides a new source of filler for the paper industry.
  • Figure 1 is a schematic view of a precipitation crystallized coating modification reaction device on the surface of fly ash
  • Figure 2 is the SEM morphology of the fly ash particles before surface modification
  • Figure 3 shows the SEM morphology of fly ash particles after surface modification.
  • the gas dispersing device 4 is at the bottom of the reaction vessel 2, and the reaction is carried out in the mixed suspension 3 above the gas dispersing device 4.
  • the gas dispersing device 4 is connected to the outside CO 2 gas tank 5 by a gas pipe for supplying CO 2 required for the reaction, and the gas flow rate is regulated by the gas flow control valve 6 on the gas pipe.
  • the rotor of the agitator 1 is placed in the mixed suspension 3 of the reaction vessel for agitation mixing of the reaction process, and the stirring rate is controlled by controlling the rotation speed thereof.
  • the mass concentration of coal ash is adjusted to 40%.
  • the CO 2 gas was introduced at a flow rate of 0.1 L /min at a stirring rate of 400 rpm. After 30 minutes, the reaction was stopped by stopping the introduction of CO 2 gas and stirring, and the whiteness was 78% ISO, and diluted with water to 5% by mass. After the concentration, it is used for paper preparation and filling.
  • the mass concentration of coal ash is adjusted to 25%.
  • the CO 2 gas was introduced at a flow rate of 0.1 L /min at a stirring rate of 300 rpm. After 30 minutes, the reaction was stopped by stopping the introduction of CO 2 gas and stirring, and the whiteness was 86% ISO, and diluted with water to 10% by mass. After the concentration, it is used for paper preparation and filling.
  • Figure 2 shows the SEM morphology of the fly ash particles before surface modification
  • Figure 3 shows the SEM morphology of the fly ash particles after surface modification. It can be clearly seen that the surface of the fly ash particles is fixed with a large number of calcium carbonate crystals whose particle size is much smaller than that of the original coal ash particles, and is uniformly arranged, which plays a certain covering role and basically maintains the granular structure, and is effectively completed to improve
  • the whiteness of fly ash is the surface coating for the purpose.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Paper (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

Abstract

一种用作造纸填料的粉煤灰表面沉淀结晶式包覆改性的方法，包括：在常温条件下，将经过摇振筛选取的粒径为30-55μm的粉煤灰与Ca(OH) 2溶液混合均匀，在搅拌条件下从反应容器底部以鼓泡法通入CO 2气体实现沉淀结晶式包覆改性。

Description

一种用作造纸填料的粉煤灰表面沉淀结晶式包覆改性的方法
技术领域
本发明属于制浆造纸工程学科的填料改性技术领域，具体涉及一种用作造纸填料的粉煤灰表面沉淀结晶式包覆改性的方法。
背景技术
粉煤灰作为发电厂锅炉煤燃烧后的副产物，是我国最大的城镇固体废弃物排放源之一。粉煤灰的堆放将会直接或间接引发大气、土壤、河流等一系列环境问题，同时造成极大的资源浪费。多年来，国内外学者通过多种方法研究粉煤灰的资源化利用技术，并在建筑、道路、污水处理、矿物提取、材料加填等多方面取得突破。但在这些领域的利用存在产品得率低、附加值不高、处理过程成本高等一系列问题。由于粉煤灰具有和造纸行业用填料高岭土相似的化学组成和独特的表面孔洞结构，可用于造纸加填。而粉煤灰颗粒中未燃尽炭、铁氧化物等发色源的干扰，使之白度仅30%ISO左右，难以满足高白度纸张加填（≧80%ISO）要求，在造纸填料领域的应用因此受到限制。
盖国胜曾提出一种先将粉煤灰在40~100oC条件下和Ca（OH）2混合，之后再在冷却至常温条件下用CO2进行中和，然后对浆料过滤并干燥，此方法主要利用高温碱性条件下粉煤灰的表面结构的变化进行改性，后期的CO2只是起到中和过量Ca（OH）2的辅助性作用。于晓东则公开了另一种粉煤灰脱色方法：先将炭含量0.1%~1%的粉煤灰完全浸泡至水中并加热至沸腾，然后通入200oC高温CO2气体充分接触5~15min后可以将白度提高至70~81%ISO，此方法在高炭含量的增白应用受到一定约束，并需要提供一定的高温环境。本发明人也曾公开一种先高温除炭再以淀粉为胶黏剂粘结PCC（沉淀碳酸钙）颗粒到粉煤灰颗粒表面的方法，此方法过程稍显复杂且需耗能，因此本发明在其基础上进行优化。
发明内容
基于以上方法存在的不足和片面性，本发明提出一种新型粉煤灰表面沉淀结晶式包覆改性方法。为了在常温条件下通过低成本的工艺原料和方案实现白度性能明显改善，同时不破坏煤灰原有的颗粒结构。
本发明方案如下。
一种用作造纸填料的粉煤灰表面沉淀结晶式包覆改性的方法，包括以下方法：
（1）原料选取：通过摇振筛选取粒径在30~55μm范围内的粉煤灰粉体颗粒作为表面改性的原料；
（2）结晶包覆：常温下将选取的粉煤灰与 Ca（OH）2 溶液的混合悬浮液，均匀混合后，在搅拌条件下，从反应容器的底部以鼓泡法通入 CO2 气体发生沉淀结晶反应，反应后，停止通入 CO2 气体和搅拌终止反应；
（ 3 ）调浓备用：用清水对反应后的混合液进行浓度调整，后作为造纸填料备用。
上述方法中，采用常温下（10~30℃）的碳化反应实现粉煤灰表面的碳酸钙沉淀结晶包覆改性，不采用任何其它预处理方法或高温条件下的物理化学反应。
上述方法中，所粉煤灰与 Ca（OH）2 溶液中的溶质 Ca（OH）2 的质量比为 0.1~3.0 ；所述粉煤灰在混合悬浮液中的质量百分比浓度为 20%~50% 。
上述方法中，所采用的包覆改性反应介质为 Ca（OH）2 溶液，并通入 CO2 在粉煤灰表面产生沉淀结晶，此外不加入其它任何化学品。
上述方法中，采用安装在反应容器底部连续鼓泡的气体分散装置，所述气体分散装置为单进气管口的曝气板。
上述方法中，所述搅拌速率控制范围为 100~600rpm ， CO2 流速控制在 0.1~1.5L/min ，反应时间为 10~60min 。
上述方法中，反应完成后获得的粉煤灰 - 碳酸钙复合体悬浮液直接调整浓度后用于纸张加填，调整后质量百分比浓度为 1%~30% 。
与现有技术相比，本发明的优势在于：
（1）原料（粉煤灰、Ca（OH）2和CO2）获取方便，成本较低，且在常温10~30oC条件下即可发生反应,适用于不同环境；
（2）直接在粉煤灰表面进行温和条件下的沉淀结晶式包覆，晶体形状为片状、针状或柱状，粒径0.5~3μm（如图3所示），不对粉煤灰优异的颗粒结构造成影响；
（3）可以通过反应条件的调控最终产品的白度性能，白度调控范围65~86%ISO，可以满足不同白度要求纸张的加填需要。
（4）湿法改性后直接调整浓度为1%~30%送入造纸机配浆系统，无需干燥后再加入，有效降低能耗。
（5）该技术为粉煤灰固体废弃物的高附加值利用提供途径，同时为造纸行业提供一种新型填料来源。
附图说明
图1为粉煤灰表面沉淀结晶式包覆改性反应装置示意图；
图2为表面改性前粉煤灰颗粒SEM形貌；
图3为表面改性后粉煤灰颗粒SEM形貌。
图中各个部件如下：
搅拌器1、反应容器2、混合悬浮液（Ca（OH）2+粉煤灰）3、 气体分散装置4、CO2气体罐5、气体流量控制阀6。
具体实施方式
下结合附图和实例对本发明的实施作进一步说明。
如图1所示实验装置，气体分散装置4处于反应容器2的底部，反应在所述气体分散装置4上方的混合悬浮液3中进行。所述气体分散装置4与外界的CO2气罐5由气管连接，用于提供反应所需CO2，并且通过气管上的气体流量控制阀6调节气体流速。同时搅拌器1的转子处于反应容器的混合悬浮液3中，用于反应过程的搅拌混合，通过控制其转速调控搅拌速率。
实施例1：
在25 ℃ 条件下按照 M 粉煤灰 ： M 氢氧化钙（溶质） =1.0 的质量比配备粉煤灰（平均粒径 40μm ）和 Ca（OH）2 混合悬浮液， 并将混合液中粉煤灰的质量浓度调整至 30% 。然后在 400rpm 搅拌速率下以 0.4L /min 流速通入 CO2 气体， 50min 后，停止通入 CO2 气体和搅拌终止反应，取样测定其白度为 73%ISO ，用清水稀释成 1% 质量百分比浓度后用于抄纸加填。
实施例 2 ：
在 25 ℃条件下按照 M 粉煤灰 ： M 氢氧化钙（溶质） =1.6 的质量比配备粉煤灰（平均粒径 40μm 左右）和 Ca（OH）2 混合悬浮液，并将混合液中粉煤灰的质量浓度调整至 40% 。 然后在 400rpm 搅拌速率下以 0.1L /min 流速通入 CO2 气体， 30min 后，停止通入 CO2 气体和搅拌终止反应，取样测定其白度为 78%ISO ， 用清水稀释成 5% 质量百分比浓度后用于抄纸加填。
实施例 3 ：
在 25 ℃条件下按照 M 粉煤灰 ： M 氢氧化钙（溶质） =0.185 的质量比配备粉煤灰（平均粒径 40μm 左右）和 Ca（ OH）2 混合悬浮液 ，并将混合液中粉煤灰的质量浓度调整至 25% 。然后在 300rpm 搅拌速率下以 0.1L /min 流速通入 CO2 气体， 30min 后， 停止通入 CO2 气体和搅拌终止反应，取样测定其白度为 86%ISO ，用清水稀释成 10% 质量百分比浓度后用于抄纸加填。
如图2所示为表面改性前粉煤灰颗粒SEM形貌，图3则为表面改性后粉煤灰颗粒SEM形貌。可以明显看到粉煤灰颗粒表面固着了大量粒径远远小于原始煤灰颗粒的碳酸钙晶体，并呈现均匀排布，起到一定的遮盖作用，并基本保持颗粒结构，有效地完成以提高粉煤灰的白度为目的的表面包覆。
本发明的上述实施例仅仅是为清楚地说明本发明所作的举例，而并非是对本发明的实施方式的限定。对于所属领域的普通技术人员来说，在上述说明的基础上还可以做出其它不同形式的变化或变动。这里无需也无法对所有的实施方式予以穷举。凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明权利要求的保护范围之内。

Claims (5)

  1. 一种用作造纸填料的粉煤灰表面沉淀结晶式包覆改性的方法，其特征在于，包括以下步骤：
    （1）原料选取：通过摇振筛选取粒径在30~55μm的粉煤灰粉体颗粒作为表面改性的原料；
    （2）结晶包覆：常温下将选取的粉煤灰与Ca（OH）2溶液的混合悬浮液，均匀混合后，在搅拌条件下，从反应容器的底部以鼓泡法通入CO2气体发生沉淀结晶反应，反应后，停止通入CO2气体和搅拌终止反应；
    （3）调浓备用：用清水对反应后的混合液进行浓度调整，后作为造纸填料备用。
  2. 根据权利要求1所述的粉煤灰表面包覆改性方法，其特征在于，所粉煤灰与Ca（OH）2溶液中的溶质Ca（OH）2的质量比为0.1~3.0；所述粉煤灰在混合悬浮液中的质量百分比浓度为20%~50%。
  3. 根据权利要求1所述的粉煤灰表面包覆改性方法，其特征在于，采用安装在反应容器底部连续鼓泡的气体分散装置，所述气体分散装置为单进气管口的曝气板。
  4. 根据权利要求1所述的粉煤灰表面包覆改性方法，其特征在于，所述搅拌速率控制范围为100~600rpm，CO2流速控制在0.1~1.5L/min，反应时间为10~60min。
  5. 根据权利要求1所述的粉煤灰表面包覆改性方法，其特征在于，反应完成后获得的粉煤灰-碳酸钙复合体悬浮液直接调整浓度后用于纸张加填，调整后质量百分比浓度为1%~30%。
PCT/CN2016/110208 2016-07-30 2016-12-15 一种用作造纸填料的粉煤灰表面沉淀结晶式包覆改性的方法 WO2018023918A1 (zh)

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