摘要
将尾矿高效活化制备辅助胶凝材料,对解决矿山环境污染和发展低碳胶凝材料有深远意义.本文归纳了尾矿的矿物属性、活化工艺、活化作用机制与活化辅助胶凝材料性能之间的关系,从矿物学角度全面阐述了尾矿通过物理、化学和表面化学作用产生活性和胶凝性的基本规律,探讨和展望了一种依据尾矿属性分析评价尾矿制备辅助胶凝材料的新思路,为尾矿制备辅助胶凝材料提供了理论和方法支持.
随着地球气候变暖的环境压力和矿山开采对生态的威胁不断加大,安全消纳矿山固废、降低CO2排放是国家健康发展和全人类友好生存的共同挑战.因此,用富含硅、铝、钙源的尾矿替代传统原材料制备辅助胶凝材料(SCM)具有良好的应用前景,其制备过程可减少CO2的排放.
采用尾矿制备的SCM在混凝土和砂浆生产中已取得较好的应
利用化学成分相图分析法评价尾矿的潜在活性,可依据化学组成中CaO2与Al2O3、Fe2O3、SiO2的质量比将尾矿分为潜在活性类、潜在水硬活性类和潜在火山灰活性类3种类型(见

图1 尾矿潜在活性分类三元相图
Fig.1 Ternary phase diagram of potential activity classification of tailings
由于尾矿的结晶度决定了其成分中有效参与化学反应活性物质的含量(质量分数,文中涉及的含量、比值等均为质量分数或质量比),导致尾矿的成分和水硬性模数不足以评价尾矿的反应性.从矿物学角度出发,不同矿物在碱性条件下的溶解性不同,尾矿的矿物组成同样影响其潜在活性.尾矿是由硅酸盐、碳酸盐、铝酸盐和磷酸盐组成的,含钙层状硅酸盐矿物(如高岭土、云母和绿泥石等)经活化处理后可产生反应活性.惰性碳酸盐(如白云石)经活化后也可产生反应性的CaO 和 MgO,活性硅、铝源可作为活性激发剂.石英、长石、辉石、闪石和云母等高硅、高铝的硅酸盐或硅铝酸盐矿物经机械活化、碱激发或热碱活化后可溶出活性硅、铝质而发挥潜在火山灰活性,当与多元活性SCM复合粉磨时,可在协同激发作用下产生潜在水硬性.因此,依据Maruthupandian

图2 矿物潜在活性分类示意图
Fig.2 Schematic diagram of mineral potential activity classification
综合分析法分为以下4步.
(1)通过分析尾矿发生硅钙反应或地聚合反应所能提供的元素组成,结合化学成分相图分析法对尾矿进行潜在活性归类,并依据水硬性模数和碱度模数分析尾矿潜在的活性来源,这是辨别尾矿是否需要碱活化的关键.
(2)依据矿物分析法鉴别尾矿矿物的潜在活性类别,由尾矿各活性分类矿物的含量评价尾矿的潜在活性.最优活化方法通过矿物属性分类来选择,如:高结晶度的硅酸盐矿物和火成岩矿物不具备自发反应的化学组成条件,因此需要优先选择降低矿物结晶度的活化方法,通过活化产生可溶解的活性硅、铝源,在化学成分矫正条件下发生硬化反
(3)选择适宜的尾矿活化方法.尾矿的活化通常需要2种以上的活化方法,方法的选择需要综合考虑.H0.2的潜在胶凝性和潜在水硬性矿物优先采用机械活化和热活化;H0.2、IA1.20的潜在火山灰活性矿物建议采用化学活化或化学复合活化.尾矿综合分析和活化方法的选择建议见

图3 尾矿综合分析和活化方法的选择建议
Fig.3 Suggestions for comprehensive analysis of tailings and selection of activation method
(4)活化性能测试、评价与表征.尾矿经活化处理后选用合适的分析方法进行活化表征.溶解法、钙吸收法、强度法和水化热法适用于碱活化的评价;X射线衍射(XRD)法、强度法和溶解法均适用于机械活化方法的评价;热重分析(TG)、XRD和水化热法适用于热活化的评价.
尾矿的活性与矿物属性相关,尾矿中高钙、高铝、晶体结构有序化程度低的矿物一般具有高反应活性,硅铝酸盐矿物经活化后可具备火山灰活性.尾矿活化后可作为水泥SCM或地聚合物胶凝材料.作为水泥SCM的尾矿可发挥其矿物学和物理化学特征,通过二次水化、晶核效应和填充效应体现胶凝特性,适用于潜在活性和潜在水硬活性尾矿.此类尾矿以机械活化为主,复合热活化、碱激发和水热作用等方式,增加尾矿活性矿物和活性位点的生成并增加反应活化能,促进水化反应并优化胶凝结构.制备地聚合物胶凝材料的尾矿可通过高碱溶出活性S
尾矿多由高结晶度的矿物组成,不直接产生胶凝性,需要使用一些活化方法来激发其水化反应性,如提高非晶化程度、增加可溶性C

图4 尾矿的活化方法
Fig.4 Activation methods of tailings
水热活化使尾矿在湿热及高pH值条件下降低其矿物结晶度,活性S
机械活化通过破碎磨削减小颗粒尺寸,降低矿物结晶度,提高矿物的反应活

图5 石英机械活化作用原理图
Fig.5 Schematic diagram of mechanical activation of quart
热活化是通过矿物结构/物相转变、硅酸二钙(C2S)相合成、脱羟基、脱碳和非晶化作用使尾矿产生活性.活化产生的活性—Si—O—、—Al—O—和C
化学活化(包括碱活化等方式)是在高pH值等化学环境下使尾矿中的矿物由晶体转变为无定形结构,产生胶结性骨架的过程.化学活化涉及合成反应,当富含硅、铝的矿物原材料与强碱性溶液混合时,S
从水化硅酸钙(C‑S‑H)体系中的反应作用机制分析,尾矿活化制备水泥SCM是通过活化尾矿中的非晶态活性硅铝酸盐,使其能与水泥水化产生的Ca(OH)2发生二次水化反
Mineral | Activation | ||
---|---|---|---|
Mechanical | Thermal | Chemistry | |
Quartz |
High efficiency, activity index achieves 75 |
Amorphous phase produces at 900 ℃ to 1 000 ℃, soluble A | 28 d compressive strength achieves 7.18 MPa with 20.0% CaO |
Feldspar |
High efficiency, activity index achieves 84 | 28 d compressive strength achieves 12.20 MPa with 20.0% CaO, 20.43 MPa with 12.5% CaO and 7.5% CaSO4 | |
Mica |
Low efficiency, activity index achieves 94 | 28 d compressive strength achieves 10.98 MPa with 20.0% CaO, 20.93 MPa with 15.0% CaO and 5.0% CaSO4 | |
Illite,kaolinite |
Hydroxyl decomposition at (750 ± 50) ℃, mullite produces and activity loses up to 800 ℃ | ||
Limestone | High efficiency and low activity |
Decompose C | |
Dolomite | Easy to grind and reunite, Low activity | ||
Sulfide | High alkali is needed | Promote the formation of ettringite | |
Iron mineral | Pozzolanic activity can be produced at 500 ℃ | ||
Chlorite |
A |
尾矿活化制备地聚合物胶凝材料,是尾矿活化后产生的地聚合物反应前体在碱激发作用下产生[AlO4
水热活化和化学活化是潜在火山灰活性尾矿制备稳定结晶态单组分地聚合物的主要方
尾矿的矿物属性决定活化的用碱量和温度,同时活化产物的力学性能也与尾矿的矿物组成相关.当尾矿以绿辉石为主要矿物时,制备的地聚合物抗压强度最高达117.3 MPa;以石英、钠长石为主要矿物时,制备的地聚合物抗压强度最高只能达到25.0 MP
综上,分析尾矿的主要矿物组成可以优选活化方法、设计凝胶结构.石英、钾/钠长石为主的高硅铝低钙尾矿,可采用强碱性碱金属活化剂,诱导SiO、AlO单体的聚合或水化产物的生成,形成非晶态类沸石相聚合网络.钙长石等含钙硅铝酸盐矿物经强碱性碱金属活化剂溶蚀后,活化剂电离的N
尾矿制备水泥SCM活化效率和反应程度的评价方法(见
Method | Advantage | Disadvantage |
---|---|---|
Dissolution |
The dissolution reaction and efficiency of active S | The reaction of tailings in cement‑based material can not reflect |
CaO absorption |
The reaction efficiency of S |
Effects without C |
TG | The new phase and the hydration products are evaluated | The activation efficiency and reaction mechanism are not intuitive |
Strength | Showing mechanical properties, more suitable | The analysis of principle is poor |
XRD | The amount of amorphous transformation and the phase change of hydration products can be shown to analyze the mechanism of reaction activity | The relationship between phase and activity needs to be established |
Hydration | Hydration capacity and efficiency are evaluated by reaction heat release | Can not reflect the change of activation properties |
Electric conductivity | The time required for material activation reaction is characterized by volcanic ash reaction | The test is affected by conductive impurity ions |
周宇
统计分析研究表明:用尾矿制备的水泥SCM替代普通水泥SCM,86%替代率会造成3%~19%的工作性能损
Item | MgO | SO3 | Na2O | Organic |
---|---|---|---|---|
Mineral | Dolomite, talcum | Sulfate, pyrite,et al | Felspar, alkali metal mineral | Clay, et al |
Perniciousness | Expansion | Sulphate | Alkalization | Slow‑setting, high porosity |
Limit(by mass)/% | ≤4.0 | 3.5 | ≤5.0 | ≤5.0 |
机械活化或热活化可提高尾矿制备的水泥SCM力学性能.机械活化影响早期力学性能,热活化影响水化特征和后期力学性能.尾矿经选矿加工和活化后,矿物表面的物理化学性质发生了改变,颗粒变细,多孔性和团聚黏附性增加,制备的水泥SEM吸水率通常可达7.15%,导致工作性能降低,外加剂吸附量增
碱活化尾矿制备的地聚合物胶凝材料比普通水泥更能抵抗酸和硫酸盐的侵蚀,具有优异的机械性能、较少的多孔结构、良好的耐腐蚀性和重金属固化能
(1)尾矿的活性与矿物属性相关,尾矿中高钙、高铝、晶体结构有序化程度低的矿物一般具有高反应活性,硅铝酸盐矿物经活化后可具备火山灰活性.
(2)尾矿中结晶度高的矿物呈惰性,活化是激发其活性的关键技术.机械活化是降低尾矿结晶度且增加活性表面的主要方法;热活化需要根据尾矿的矿物属性,采用热分析法确定合理的活化温度以达到预定的活化效果;化学活化是尾矿转变为非晶态最有效的方法.“低钙高碱、高钙低碱”原则适用于活化剂的选择,活化剂类型会影响水化胶凝产物及微观结构.
(3)尾矿制备水泥SCM的可行方案主要有3类:通过多种活化方式协同,使尾矿溶出活性基团,在碱性条件下与辅助活性材料协同反应生成新生水化产物和紧密结构;通过碱-熔、碱-热作用使尾矿溶解,通过反应条件的调控合成地聚合物;通过高温煅烧使尾矿生成具有水化胶凝性的新矿相,这种活化方式一般需要含有高钙矿物或高岭土.
(4)尾矿制备的水泥SCM性能与替代率成反比,建议替代率不大于25%.碱激发尾矿制备的地聚合物胶凝材料具有更优异的性能,尾矿制备低碳胶凝材料的研究未来仍然具有创新性和挑战性.
参考文献
YUN W C, YONG J K, CHOI O, et al. Utilization of tailings from tungsten mine waste as a substitution material for cement[J]. Construction and Building Materials, 2009, 23(7):2481‑2486. [百度学术]
ONUAGULUCHI O, EREN O. Cement mixtures containing copper tailings as an additive:Durability properties[J]. Materials Research, 2012, 15:1029‑1036. [百度学术]
SIMONSEN A M T, SOLISMAA S, HANSEN H K, et al. Evaluation of mine tailings’ potential as supplementary cementitious materials based on chemical, mineralogical and physical characteristics[J]. Waste Management, 2020, 102:710‑721. [百度学术]
BAGGER A M T, KUNTHER W, SIGVARDSEN N M, et al. Screening for key material parameters affecting early‑age and mechanical properties of blended cementitious binders with mine tailings[J]. Case Studies in Construction Materials, 2021, 15:e00608. [百度学术]
KIVENTER J, PERUMAL P, YLINIEMI J, et al. Mine tailings as a raw material in alkali activation:A review, international journal of minerals[J]. Metallurgy and Materials, 2020, 27(8):1009‑1020. [百度学术]
SAEDI A, ZANJANI A J, KHODADADI‑DARBAN A. A review on different methods of activating tailings to improve their cementitious property as cemented paste and reusability[J]. Journal of Environmental Management, 2020, 270:110881. [百度学术]
PERUMAL P, KIVENTERÄ J, ILLIKAINEN M. Influence of alkali source on properties of alkali activated silicate tailings[J]. Materials Chemistry and Physics, 2021, 271:124932. [百度学术]
SICAKOVA A, KOVAC M. Technological characterisation of selected mineral additives[J]. IOP Conference Series:Materials Science and Engineering, 2018, 385(1):0112408. [百度学术]
SHI C J, ROY D, KRIVENKO P. Alkali‑activated cements and concretes[M]. London:CRC Press, 2006:104‑126. [百度学术]
MARUTHUPANDIAN S, CHALIASOU A, KANELLO‑POULOS A. Recycling mine tailings as precursors for cementitious binders-Methods, challenges and future outlook[J]. Construction and Building Materials, 2021, 312:125333. [百度学术]
姚耿. 机械活化硅质尾矿水化反应特性研究[D]. 青岛:山东科技大学, 2020. [百度学术]
YAO Geng. Characterization of hydration reaction of mechanically activated siliceous tailings[D]. Qingdao:Shandong University of Science and Technology, 2020. (in Chinese) [百度学术]
VARGAS F, MAURICIO L. Development of a new supplementary cementitious material from the activation of copper tailings:Mechanical performance and analysis of factors[J]. Journal of Cleaner Production, 2018, 182:427‑436. [百度学术]
KIVENTERA J, SREENIVASAN H, CHEESEMAN C, et al. Immobilization of sulfates and heavy metals in gold mine tailings by sodium silicate and hydrated lime[J]. Journal of Environmental Chemical Engineering, 2018, 6:6530‑6536. [百度学术]
WEI B, ZHANG Y M, BAO S X. Preparation of geopolymers from vanadium tailings by mechanical activation[J]. Construction and Building Materials, 2017, 145:236‑242. [百度学术]
YAO G, LIU Q, WANG J X, et al. Effect of mechanical grinding on pozzolanic activity and hydration properties of siliceous gold ore tailings[J]. Journal of Cleaner Production, 2019, 217:12‑21. [百度学术]
MAKO E, FROST R L, KRISTOF J, et al. The Effect of quartz content on the mechanochemical activation of kaolinite[J]. Journal of Colloid and Interface Science, 2001, 244:359‑364. [百度学术]
COCCO C, GARRONI S, ENZO S, et al. Ball milling of silica‑based pyroclastic scoriae:Measurement of mechanochemical reactivity by radical scavenging[J]. The Journal of Physical Chemistry C, 2018, 122:2773‑2782. [百度学术]
PACHECO‑TORGAL F, CASTRO‑GOMES J, JALALI S, et al. Investigations about the effect of aggregates on strength and microstructure of geopolymeric mine waste mud binders[J]. Cement and Concrete Research, 2007, 37:933‑941. [百度学术]
李北星, 陈梦义, 王威, 等. 梯级粉磨制备铁尾矿-矿渣基胶凝材料[J]. 建筑材料学报, 2014, 17(2):206‑211. [百度学术]
LI Beixing, CHEN Mengyi, WANG Wei, et al. Preparation of iron tailings and slag based cementing materials by step grinding [J]. Journal of Building Materials, 2014, 17(2):206‑211. (in Chinese) [百度学术]
CHENG Y H, HUANG F, LI W C, et al. Test research on the effects of mechanochemically activated iron tailings on the compressive strength of concrete[J]. Construction and Building Materials, 2016, 118:164‑170. [百度学术]
PENG K, YANG H M, OUYANG J. Tungsten tailing powders activated for use as cementitious material[J]. Powder Technology, 2015, 286:678‑683. [百度学术]
NIU H, HELSER J, CORFE I J, et al. Incorporation of bioleached sulfidic mine tailings in one‑part alkali‑activated blast furnace slag mortar[J]. Construction and Building Materials, 2022, 333:127195. [百度学术]
张钊. 碳酸盐粉体对砂浆性能的影响研究[D]. 重庆:重庆大学, 2016. [百度学术]
ZHANG Zhao. Research on the effect of carbonate powder on mortar properties[D]. Chongqing:Chongqing University, 2016. (in Chinese) [百度学术]
刘数华, 阎培渝. 石灰石粉在复合胶凝材料中的水化性能[J]. 硅酸盐学报, 2008(10):1401‑1405. [百度学术]
LIU Shuhua, YAN Peiyu. Hydration properties of limestone powder in composite cementitious materials[J]. Journal of the Chinese Ceramic Society, 2008(10):1401‑1405. (in Chinese) [百度学术]
FERNANDEZ R, MARTIRENA F, SCRIVENER K L. The origin of the pozzolanic activity of calcined clay minerals:A comparison between kaolinite, illite and montmorillonite[J]. Cement and Concrete Research, 2011, 41:113‑122. [百度学术]
LI C, WAN J H, SUN H H, et al. Investigation on the activation of coal gangue by a new compound method[J]. Journal of Hazardous Materials, 2010, 179(1‑3):515‑520. [百度学术]
PROVIS J L. Alkali activated materials[J]. Cement and Concrete Research, 2018, 114:40‑48. [百度学术]
ZHAO Y L, QIU J P, GUO Z B, et al. Activation the hydration properties of illite‑containing tailings to prepare a binder for cemented paste backfill[J]. Construction and Building Materials, 2022, 318:125989. [百度学术]
YU L, ZHANG Z, HUANG X, et al. Enhancement experiment on cementitious activity of copper‑mine tailings in a geopolymer system[J]. Fibers, 2017, 5(4):47. [百度学术]
KIVENTERA J, LANCELLOTTI I, CATAURO M, et al. Alkali activation as new option for gold mine tailings inertization[J]. Journal of Cleaner Production, 2018, 187:76‑84. [百度学术]
周宇, 徐方, 顾功辉, 等. 地聚合物早期抗压强度及分子动力学模拟[J]. 建筑材料学报, 2021, 24 (1):93‑98, 120. [百度学术]
ZHOU Yu, XU Fang, GU Gonghui, et al. Early compressive strength and molecular dynamics simulation of geopolymers [J]. Journal of Building Materials, 2021, 24 (1):93‑98, 120. (in Chinese) [百度学术]
SHI C J, QU B, PROVIS J L. Recent progress in low‑carbon binders [J]. Cement and Concrete Research, 2019, 122:227‑250. [百度学术]
KE X Y, BERNAL S A, YE N, et al. One‑part geo‑polymers based on thermally treated red mud/NaOH blends[J]. Journal of the American Ceramic Society, 2015, 98(1):5‑11. [百度学术]
LIN W Q, ZHOU F Y, LUO W J, et al. Effect of alkali cation type on compressive strength and thermal performance of the alkali‑activated omphacite tailing [J]. Construction and Building Materials, 2021, 306:124647. [百度学术]
BAO S X, LUO Y P, ZHANG Y M. Fabrication of green one‑part geopolymer from silica‑rich vanadium tailing via thermal activation and modification[J]. International Journal of Minerals, Metallurgy and Materials, 2022, 29:177‑184. [百度学术]
CIHANGIR F, ERCIKDI B, KESIMAL A, et al. Utilisation of alkali‑activated blast furnace slag in paste backfill of high‑sulphide mill tailings:Effect of binder type and dosage[J]. Minerals Engineering, 2012, 30:33‑43. [百度学术]
TIAN X, XU W Y, SONG S X, et al. Effects of curing temperature on the compressive strength and microstructure of copper tailing‑based geopolymers[J]. Chemosphere, 2020, 253:126754. [百度学术]
LIU Q, LI X C, CUI M Y, et al. Preparation of eco‑friendly one‑part geopolymers from gold mine tailings by alkaline hydrothermal activation[J]. Journal of Cleaner Production, 2021, 298:126806. [百度学术]
WAN Q, RAO F, SONG S X, et al. Consolidation of mine tailings through geopolymer‑ization at ambient temperature[J]. Journal of the American ceramic society, 2019,102(5):2451‑2461. [百度学术]
郑蕻陈,刘琳.碱激发体系凝结时间和早期抗压强度变化规律[J].建筑材料学报,2023,26(11):1214‑1219. [百度学术]
ZHENG Hongchen, LIU Lin. Variation of coagulation time and early compressive strength of alkali excitation system[J]. Journal of Building Materials, 2019,26(11):1214‑1219. (in Chinese) [百度学术]
ESPEJEL‑AYALA F, SOLIS‑LOPEZ M, SCHOUWENAARS R, et al. Sintesis de zeolita P utilizando jales de cobre[J]. Revista Mexicana de Ingeniería Química, 2015, 14(1):205‑212. [百度学术]
殷义栋, 鲁安怀, 李艳, 等.大庆油田三元复合驱液与储层矿物反应性研究[J]. 岩石矿物学杂志, 2015, 34(6):811‑820. [百度学术]
YIN Yidong, LU Anhuai, LI Yan, et al. Study on reactivity of ternary compound flooding and reservoir minerals in Daqing Oilfield [J]. Journal of Petromineralogy, 2015, 34(6):811‑820. (in Chinese) [百度学术]
LUXAN M P, MADRUGA F, SAAVEDRA J. Rapid evaluation of pozzolanic activity of natural products by conductivity measurement[J]. Cement and Concrete Research, 1989, 19(1), 63‑68. [百度学术]
SICAKOVA A, KOVAC M. Technological characterisation of selected mineral additives[J]. IOP Conference Series:Materials Science and Engineering, 2018, 385:012048. [百度学术]
INCE C. Reusing gold‑mine tailings in cement mortars:Mechanical properties and socio‑economic developments for the Lefke‑Xeros area of Cyprus[J]. Journal of Cleaner Production, 2019, 238:117871. [百度学术]
林伟青, 周方圆, 罗文君, 等. 养护温度对白云岩碱激发净浆断裂性能的影响[J]. 建筑材料学报, 2022, 25(7):672‑676, 729. [百度学术]
LIN Weiqing, ZHOU Fangyuan, LUO Wenjun, et al. Effect of curing temperature on fracture performance of dolomite alkali excited pure pulp [J]. Journal of Building Materials, 2022, 25(7):672‑676, 729. (in Chinese) [百度学术]