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Evolution and Application of Sealing Ability of Gypsum Caprocks under Temperature-Pressure Coupling:An Example of the ZS5 Well in the Tazhong Area of the Tarim Basin
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作者 LIU Hua ZHAO Shan +3 位作者 YANG Xianzhang ZHU Yongfeng WANG Shen ZHANG Ke 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2024年第1期168-184,共17页
Gypsum caprocks'sealing ability is affected by temperature-pressure coupling.Due to the limitations of experimental conditions,there is still a lack of triaxial stress-strain experiments that simultaneously consid... Gypsum caprocks'sealing ability is affected by temperature-pressure coupling.Due to the limitations of experimental conditions,there is still a lack of triaxial stress-strain experiments that simultaneously consider changes in temperature and pressure conditions,which limits the accuracy of the comprehensive evaluation of the brittle plastic evolution and sealing ability of gypsum rocks using temperature pressure coupling.Triaxial stress-strain tests were utilized to investigate the differences in the evolution of the confinement capacity of gypsum rocks under coupled temperaturepressure action and isothermal-variable pressure action on the basis of sample feasibility analysis.According to research,the gypsum rock's peak and residual strengths decrease under simultaneous increases in temperature and pressure over isothermal pressurization experimental conditions,and it becomes more ductile.This reduces the amount of time it takes for the rock to transition from brittle to plastic.When temperature is taken into account,both the brittle–plastic transformation's depth limit and the lithological transformation of gypsum rocks become shallower,and the evolution of gypsum rocks under variable temperature and pressure conditions is more complicated than that under isothermal pressurization.The sealing ability under the temperature-pressure coupling is more in line with the actual geological context when the application results of the Well#ZS5 are compared.This provides a theoretical basis for precisely determining the process of hydrocarbon accumulation and explains why the early hydrocarbon were not well preserved. 展开更多
关键词 temperature-pressure coupling gypsum caprocks brittle-plastic evolution sealing capacity Tarim Basin
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Resource utilization of hazardous gypsum sludge in oxidation smelting of lead concentrate
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作者 PAN Zu-chao RUAN Bo-wen +2 位作者 JIAO Fen QIN Wen-qing LIU Wei 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第9期3103-3118,共16页
Gypsum sludge,a hazardous waste generated by the non-ferrous smelting industry,presents a significant challenge for disposal and utilization.To investigate the feasibility of substituting gypsum sludge for limestone a... Gypsum sludge,a hazardous waste generated by the non-ferrous smelting industry,presents a significant challenge for disposal and utilization.To investigate the feasibility of substituting gypsum sludge for limestone as a flux for smelting,the effects of calcium sulfate(CaSO_(4))and smelting conditions on oxygen-rich smelting of lead concentrate were studied.The interaction between CaSO_(4)and sulfides facilitates the conversion of CaSO_(4)into CaO,which is crucial for slag formation.The order of the influence of sulfide minerals on the conversion of CaSO_(4)is pyrite>sphalerite>galena.When using gypsum sludge exclusively as the calcium source,under optimal conditions with a CaO/SiO_(2)mass ratio of 0.8,an FeO/SiO_(2)mass ratio of 1.2,a melting temperature of 1150℃,an oxygen flow rate of 1.3 L/min,the recovery rates of Pb and Zn in the lead-rich slag reached 85.01%and 95.69%,respectively,with a sulfur content of 2.65 wt%.The As content in the smelting slag obtained by reduction smelting was 0.02 wt%.Resource utilization of gypsum sludge in lead smelting is a feasible method. 展开更多
关键词 gypsum sludge calcium sulfate resource utilization SMELTING
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Gypsum-based Silica Gel Humidity-controlling Composite Materials:Preparation,Characterization,and Performance
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作者 李曦 冉茂宇 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第2期337-344,共8页
Gypsum was used as substrate,and silica gel was mixed into substrate at a certain mass ratio to prepare humidity-controlling composites;moreover,the moisture absorption and desorption properties of gypsum-based compos... Gypsum was used as substrate,and silica gel was mixed into substrate at a certain mass ratio to prepare humidity-controlling composites;moreover,the moisture absorption and desorption properties of gypsum-based composites were compared with adding different silica gel particle size and proportion.The morphological characteristics,the isothermal equilibrium moisture content curve,moisture absorption and desorption rate,moisture absorption and desorption stability,and humidity-conditioning performance were tested and analyzed.The experimental results show that,compared with pure-gypsum,the surface structure of the gypsum-based composites is relatively loose,the quantity,density and aperture of the pores in the structure increase.The absorption and desorption capacity increase along with the increase of silica gel particle size and silica gel proportion.When 3 mm silica gel particle size is added with a mass ratio of 40%,the maximum equilibrium moisture content of humidity-controlling composites is 0.161 g/g at 98% relative humidity(RH),3.22 times that of pure-gypsum.The moisture absorption and desorption rates are increased,the equilibrium moisture absorption and desorption rates are 2.68 times and 1.61 times that of pure-gypsum at 58.5% RH,respectively.The gypsum-based composites have a good stability,which has better timely response to dynamic humidity changes and can effectively regulate indoor humidity under natural conditions. 展开更多
关键词 humidity controlling composite materials gypsum silica gel
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Deterioration Reason and Improvement Measure of the Retarding Effect of Protein Retarder on Phosphorus Building Gypsum
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作者 刘志刚 TANG Zezheng +3 位作者 杨立荣 WANG Chunmei XIE Yuantao LIU Yisen 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第4期962-967,共6页
The retarding effect of protein retarder on phosphorus building gypsum(PBG)and desulfurization building gypsum(DBG)was investigated,and the results show that protein retarder for DBG can effectively prolong the settin... The retarding effect of protein retarder on phosphorus building gypsum(PBG)and desulfurization building gypsum(DBG)was investigated,and the results show that protein retarder for DBG can effectively prolong the setting time and displays a better retarding effect,but for PBG shows a poor retarding effect.Furthermore,the deterioration reason of the retarding effect of protein retarder on PBG was investigated by measuring the pH value and the retarder concentration of the liquid phase from vacuum filtration of PBG slurry at different hydration time,and the measure to improve the retarding effect of protein retarding on PBG was suggested.The pH value of PBG slurry(<5.0)is lower than that of DBG slurry(7.8-8.5).After hydration for 5 min,the concentration of retarder in liquid phase of DBG slurry gradually decreases,but in liquid phase of PBG slurry continually increases,which results in the worse retarding effect of protein retarder on PBG.The liquid phase pH value of PBG slurry can be adjusted higher by sodium silicate,which is beneficial to improvement in the retarding effect of the retarder.By adding 1.0%of sodium silicate,the initial setting time of PBG was efficiently prolonged from 17 to 210 min,but little effect on the absolute dry flexural strength was observed. 展开更多
关键词 protein retarder phosphorus building gypsum deterioration reason improvement measure
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Deep decalcification of factory-provided freezing acidolysis solution to achieveα-high-strength gypsum
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作者 Wencai Ye Yulu Li +3 位作者 Yonggang Dong Lin Yang Yun Yi Jianxin Cao 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2024年第5期143-151,共9页
The freezing acidolysis solution of the nitric acid-phosphate fertilizer process has a high calcium content,which makes it difficult to produce fine phosphate and high water-soluble phosphate fertilizer products.Here,... The freezing acidolysis solution of the nitric acid-phosphate fertilizer process has a high calcium content,which makes it difficult to produce fine phosphate and high water-soluble phosphate fertilizer products.Here,based on the potential crystallization principle of calcium sulfate in NH_(4)NO_(3)-H_(3)PO_(4)-H_(2)O,the deep decalcification(i.e.calcium removal)technology to achieveα-high-strength gypsum originated from freezing acidolysis-solutions has been firstly proposed and investigated.Typically,calcium can be removed from the factory-provided freezing acidolysis-solution by neutralizing it with ammonia,followed by the addition of ammonium sulfate solution.As a result,the formation of calcium sulfate in the reaction system undergoes the nucleation and growth of CaSO_(4)·2H_(2)O(DH),as well as its dissolution and crystallization into short columnarα-CaSO_(4)·0.5H_(2)O(α-HH).Remarkably,with the molar ratio of SO_(4)^(2-)/Ca^(2+)at 1.8,the degree of neutralization(NH_(3)/HNO_(3) molar ratio)at 1.7,the reaction temperature of 94℃,and the reaction time of 300 min,the decalcification rate can reach 86.89%,of which the high-strengthα-CaSO_(4)·0.5H_(2)O(α-HH)will be obtained.Noteworthy,the deep decalcification product meets the standards for the production of fine phosphates and highly water-soluble phosphate fertilizers.Consequently,the 2 h flexural strength ofα-HH is 5.3 MPa and the dry compressive strength is 36.8 MPa,which is up to the standard of commercialα-HH. 展开更多
关键词 Nitrophosphate Ammonia neutralization Deep decalcification High-strengthα-hemihydrate gypsum Controlled crystallization at atmospheric pressure
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Enhanced dealkalization of bauxite residue through calcium-activated desulfurization gypsum
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作者 Yu-jun WU Sheng-guo XUE +4 位作者 Li-ping LIU Feng LI Graeme J.MILLAR Fei GE Jiang TIAN 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2024年第10期3412-3424,共13页
A novel integrated approach to remove the free alkalis and stabilize solid-phase alkalinity by controlling the release of Ca from desulfurization gypsum was developed.The combination of recycled FeCl_(3)solution and E... A novel integrated approach to remove the free alkalis and stabilize solid-phase alkalinity by controlling the release of Ca from desulfurization gypsum was developed.The combination of recycled FeCl_(3)solution and EDTA activated desulfurization gypsum lowered the bauxite residue pH to 7.20.Moreover,it also improved the residual Ca state,with its contribution to the total exchangeable cations increased(68%-92%).Notably,the slow release of exchangeable Ca introduced through modified desulfurization gypsum induced a phase transition of the alkaline minerals.This treatment stabilized the dealkalization effect of bauxite residue via reducing its overall acid neutralization capacity in abating pH rebound.Hence,this approach can provide guidance for effectively utilizing desulfurization gypsum to achieve stable regulation of alkalinity in bauxite residue. 展开更多
关键词 bauxite residue desulfurization gypsum EDTA activation alkalinity regulation recycled FeCl_(3)
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Effect of Low pH on Forming Process of Desulfurization Gypsum Composite Boards Strengthened by Melamine-formaldehyde Resin
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作者 CAO Lijiu ZHANG Jiyao +4 位作者 WANG Xinqi ZHANG Xinhe HUANG Jian CHEN Yufang JIN Tao 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第5期1223-1228,共6页
Through exploring the effects of low pH on the composite system of desulfurization gypsum(DG)enhanced by melamine-formaldehyde resin(MF),it is found that the inducing of sulfate-ion,in contrast to chloride and oxalate... Through exploring the effects of low pH on the composite system of desulfurization gypsum(DG)enhanced by melamine-formaldehyde resin(MF),it is found that the inducing of sulfate-ion,in contrast to chloride and oxalate ions,favors the longitudinal growth of the crystalline form of the hydration product,which was relatively simple and had the highest length to width(L/D)ratio.At the same time,MF can also improve L/D ratio of gypsum hydration products,which favors the formation of hydrated whiskers.Finally,in a composite system composed of hemihydrate gypsum,MF,and glass fibers,when dilute sulfuric acid was used to regulate pH=3-4,the tight binding formed among the components of the composite system compared to pH=5-6.The hydration product of gypsum adheres tightly to glass fiber surface and produces a good cross-linking and binding effect with MF.The flexural strength,compressive strength,elastic modulus,and water absorption of the desulphurized gypsum composite board is 22.7 MPa,39.8 MPa,5608 MPa,and 1.8%,respectively. 展开更多
关键词 MF-reinforced desulphurized gypsum board composite forming system low pH condition hydration process aspect ratio synergistic effect
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Preparation of α-High Strength Gypsum from Flue Gas Desulfurization Gypsum Pretreated by Hydrothermal-aging Method
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作者 苏一鑫 GAO Lili +3 位作者 陈学青 LI Zhishui 李雲 CAO Jilin 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第1期75-81,共7页
The synthesis of α-calcium sulfate hemihydrate (α-CSH) from flue gas desulfurization (FGD)gypsum is a good way to realize the comprehensive utilization of FGD gypsum. To obtainα-CSH with the satisfactory performanc... The synthesis of α-calcium sulfate hemihydrate (α-CSH) from flue gas desulfurization (FGD)gypsum is a good way to realize the comprehensive utilization of FGD gypsum. To obtainα-CSH with the satisfactory performances, a facile hydrothermal-aging pretreatment process for FGD gypsum raw materials was proposed, where FGD gypsum was firstly hydrothermally converted to α-CSH whiskers, and α-CSH whiskers were further hydrated to synthesize CaSO4·2H2O (CSD) by aging under the regulation of N,N'-methylenebisacrylamide (MBA). The effects of aging time, MBA addition, aging temperature, and pH on the morphology of the synthesized CSD were investigated. The synthesized CSD crystals exhibit highly uniform prismatic morphology with the length of ca 100μm and the whiteness of 91.56%. The regulation mechanism of MBA was also illustrated. The synthesized CSD crystals with prismatic morphology were further used as raw materials to synthesize the short columnar α-CSH. The absolute dry compressive strength of paste prepared from the short columnar α-CSH is 40.85 MPa, which reaches α40 strength grade. 展开更多
关键词 flue gas desulphurization gypsum α-calcium sulfate hemihydrate hydrothermal-aging method N N'-methylenebisacrylamide prismatic CSD
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Effect of integration of mechanical ball milling and flue gas desulfurization gypsum on dealkalization of bauxite residue
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作者 Feng ZHU Xu-yao GUO +6 位作者 Jun JIANG Kai-bin CHEN Xuan-zhi ZHU Dan-dan DENG Yu-jun WU Yu-wei HUANG Sheng-guo XUE 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2024年第8期2702-2713,共12页
The synergistic impact of mechanical ball milling and flue gas desulfurization(FGD)gypsum on the dealkalization of bauxite residue was investigated through integrated analyses of solution chemistry,mineralogy,and micr... The synergistic impact of mechanical ball milling and flue gas desulfurization(FGD)gypsum on the dealkalization of bauxite residue was investigated through integrated analyses of solution chemistry,mineralogy,and microtopography.The results showed a significant decrease in Na_(2)O content(>30 wt.%)of FGD gypsum-treated bauxite residue after 30 min of mechanical ball milling.Mechanical ball milling resulted in differentiation of the elemental distribution,modification of the minerals in crystalline structure,and promotion in the dissolution of alkaline minerals,thus enhancing the acid neutralization capacity of bauxite residue.5 wt.%FGD gypsum combined with 30 min mechanical ball milling was optimal for the dealkalization of bauxite residue. 展开更多
关键词 bauxite residue alkalinity regulation flue gas desulfurization gypsum mechanical activation soil formation of bauxite residue
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New Data on Coal, Gypsum, Iron and Silica Sand Deposits and Geochemical Exploration (Pakistan): Revision of 25 Years History of Dinosaur Discoveries from Pakistan
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作者 Muhammad Sadiq Malkani 《Open Journal of Geology》 CAS 2024年第3期431-511,共81页
Discoveries of many coal seams at depths by drilling carried by Geological Survey of Pakistan in Sor Range and Harnai Gochina, extended the coal seams at depth which is challenge for mine owners to exploit feasibly. B... Discoveries of many coal seams at depths by drilling carried by Geological Survey of Pakistan in Sor Range and Harnai Gochina, extended the coal seams at depth which is challenge for mine owners to exploit feasibly. Bed to bed gypsum samplings (and their chemical analyses) of huge gypsum deposits from Sulaiman foldbelt is a base for industrialist and also planers to develop cement and gypsum industries to increase export and foreign exchange for the development of area and Pakistan. Low and high grade sedimentary iron deposits, silica sand and uranium host rocks and their extensions in Sulaiman and Kirthar foldbelts are presented. Anomalies of a few base metals arise as a result of geochemical exploration carried at part of Loralai District of Balochistan. Theropod dinosaurs were frequent in India, while Poripuchian titanosaurs (Sauropoda, Dinosauria) were frequent in Pakistan. Besides some ichnotaxa, many bone taxa such as 1 titanosauriform, 14 titanosaurian sauropod (including one new titanosaur), and 3 theropod dinosaurs are established from Pakistan. Among these 12 titanosaur species and 3 theropod species are named in about 10 km<sup>2</sup> area of Vitakri dome and 2 titanosaur species are named in about a few hundred square meter area of Mari Bohri (Kachi Bohri) which is about 10 km westward from Vitakri dome. Pakistan is a unique country which discoverd 14 diversified titanosaurs in a short area and also in a short period (67 - 66 million years ago/Ma). About 400 bones found from a few meter thick upper part of upper shale horizon of latest Maastrichtian Vitakri Formation which is base for titanosaur taxa. Cranial material is in low fraction (but include significant diverse snouts), caudal vertebrae are prominent, the cervicals, dorsals and sacrals have significant numbers, forelimb and hind limb bones have balanced fraction. Humeri, femora and tibiae are most common. To know the position of Pakistani titanosaurs among titanosaurs and sauropods, there is a need to extend list of characters for phylogenetic analyses. This broad feature list should include main characters of titanosaurs from Pakistan and also from global world. 展开更多
关键词 COAL gypsum IRONSTONE Silica sands Geochemical Exploration Dinosaurs TITANOSAURIFORMES Titanosaurs Theropods REVISION BALOCHISTAN Pakistan
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Efficacy of borneol-gypsum in skin regeneration and pain control in toxic epidermal necrolysis:A case report
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作者 Lu-Wei Yang Li-Juan Zhang +7 位作者 Bin-Bin Zhou Xin-Yu Lin Yu-Ting Chen Xiao-Yu Qin Hui-Ying Tian Li-Li Ma Ying Sun Lin-Di Jiang 《World Journal of Clinical Cases》 SCIE 2024年第7期1290-1295,共6页
BACKGROUND Toxic epidermal necrolysis(TEN)is a life-threatening dermatological emergency mainly induced by drug hypersensitivity reactions.Standard management includes discontinuation of culprit drug and application o... BACKGROUND Toxic epidermal necrolysis(TEN)is a life-threatening dermatological emergency mainly induced by drug hypersensitivity reactions.Standard management includes discontinuation of culprit drug and application of immunomodulatory therapy.However,mortality remains high due to complications like septic shock and multiorgan failures.Innovative approaches for skin care are crucial.This report introduces borneol-gypsum,a traditional Chinese drug but a novel dressing serving as an adjuvant of TEN therapy,might significantly improve skin conditions and patient outcomes in TEN.CASE SUMMARY A 38-year-old woman diagnosed with eosinophilic granulomatosis with polyangiitis experienced gangrenous complications and motor nerve involvement.After initial treatment of high-dose corticosteroids and cyclophosphamide,symptom of foot drop improved,absolute eosinophil counts decreased,while limb pain sustained.Duloxetine was added to alleviate her symptom.Subsequently,TEN developed.Additional topical application of borneol-gypsum dressing not only protected the skin lesions from infection but also significantly eased localized pain.This approach demonstrated its merit in TEN management by promoting skin healing and potentially reducing infection risks.CONCLUSION Borneol-gypsum dressing is a promising adjuvant that could significantly improve TEN management,skin regeneration,and patient comfort. 展开更多
关键词 Toxic epidermal necrolysis Eosinophilic granulomatosis with polyangiitis DULOXETINE BORNEOL gypsum Case report
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Activation of Anhydrate Phosphogypsum by K_2SO_4 and Hemihydrate Gypsum 被引量:4
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作者 杨敏 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2011年第6期1103-1107,共5页
Lime pretreated phosphogypsum(PG) was calcined at 500 ℃ to produce anhydrate gypsum cement. Due to the slow hydration of anhydrate gypsum, additives, K2SO4 and hemihydrate gypsum were selected to accelerate the hyd... Lime pretreated phosphogypsum(PG) was calcined at 500 ℃ to produce anhydrate gypsum cement. Due to the slow hydration of anhydrate gypsum, additives, K2SO4 and hemihydrate gypsum were selected to accelerate the hydration of anhydrate. The hydration characteristics, the resistance to hydrodynamic water, and the mineralogical studies were investigated. The experimental results suggest that activated by K2SO4 and hemihydrate, anhydrate PG hydrates much more rapidly than that in the presence of only K2SO4 or in the absence of additives. The binder has proper setting time, good strength development, and relatively better resistance to water. The hardened binder has hydrated products of rod or stick like shaped dihydrate gypsum crystals. 展开更多
关键词 ACTIVATION anhydrate phosphogypsum hemihydrate gypsum HYDRATION
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Promotion of conversion activity of flue gas desulfurization gypsum into α-hemihydrate gypsum by calcination-hydration treatment 被引量:4
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作者 GUAN Qing-jun SUN Wei +5 位作者 GUAN Chang-ping YU Wei-jian ZHU Xiang-nan Sultan Ahmed KHOSO WANG Ping PENG Wen-qing 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第12期3213-3224,共12页
The massive accumulation of flue gas desulfurization(FGD)gypsum produced in the wet limestone-gypsum flue gas desulfurization process not only encroaches on lands but also causes serious environmental pollution.The pr... The massive accumulation of flue gas desulfurization(FGD)gypsum produced in the wet limestone-gypsum flue gas desulfurization process not only encroaches on lands but also causes serious environmental pollution.The preparation ofα-hemihydrate gypsum(α-HH)is an important way to achieve high-value utilization of FGD gypsum.Although the glycerol-water solution approach can be used to produceα-HH from FGD gypsum under mild conditions,the transition is kinetically unfavorable in the mixed solution.Here,an easy pretreatment was used to activate FGD gypsum by calcination and hydration to readily complete the transition.The pretreatment deteriorated the crystallinity of FGD gypsum and caused it to form small irregular flaky crystals,which dramatically increased the specific surface area.Additionally,most of the organics adsorbed onto FGD gypsum surfaces were removed after pretreatment.The poor crystallinity,increased specific surface area,and elimination of organics adsorbed onto crystal surfaces effectively improved the conversion activity of FGD gypsum,thereby promoting dihydrate gypsum(DH)dissolution andα-HH nucleation.Overall,the phase transition of FGD gypsum toα-HH is facilitated. 展开更多
关键词 flue gas desulfurization gypsum α-hemihydrate gypsum calcination-hydration treatment DISSOLUTION surface characteristics
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Thermal Dehydration Kinetics of Gypsum and Borogypsum under Non-isothermal Conditions 被引量:2
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作者 I.Y.Elbeyli S.Piskin 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2004年第2期302-305,共4页
Thermal dehydration of gypsum and borogypsum was investigated under nonisothermal conditions in air by using simultaneous thermogravimetric-differential thermal analyzer. Nonisothermal experiments were carried out at ... Thermal dehydration of gypsum and borogypsum was investigated under nonisothermal conditions in air by using simultaneous thermogravimetric-differential thermal analyzer. Nonisothermal experiments were carried out at various linear heating rates. Kinetics of dehydration in the temperature range of 373-503 K were evaluated from the DTA (differential thermal analysis)-TGA (thermogravimetric analysis) data by means of Coats-Redfern,Kissinger and Doyle Equations. Values of the activation energy and the pre-exponential factor of the dehydration were calculated. The results of thermal experiments and kinetic parameters indicated that borogypsum is similar to gypsum from dehydration mechanism point of view although it consists of boron and small amount of alkali metal oxides. 展开更多
关键词 gypsum borogypsum differential thermal analysis THERMOGRAVIMETRICANALYSIS KINETICS
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Chao HUANG,Main Factors Affecting the Improving Efficiency of Gypsum for Solonetzic Soil
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作者 赵锦慧 何超 +2 位作者 黄超 龙杰 谢子瑞 《Agricultural Science & Technology》 CAS 2016年第2期367-373,378,共8页
In order to more efficiently utilize gypsum to improve meadow alkali soil slightly salinized by soda and sulfate chloride, a total of 27 treatments were de- signed from the perspectives of field capacity, alkalinity, ... In order to more efficiently utilize gypsum to improve meadow alkali soil slightly salinized by soda and sulfate chloride, a total of 27 treatments were de- signed from the perspectives of field capacity, alkalinity, alkaline salt content, optimal irrigation, gypsum conversion, gypsum and soil treatment and improvement depth. The ions on the obtained filtrate were analyzed in terms of salts. The improving ef- ficiency of gypsum for meadow alkali soil was analyzed through comparing the con- tents of soluble salts in pre-improvement and post-improvement soil by reasoning and calculation. The results showed that, (1) the dissolved amount and conversion amount of gypsum were increased, and the soil alkalinity was decreased corre- spondingly with the increased irrigation amount. However, after reaching a certain extent, the linear relationships became unobvious gradually. Therefore, the irrigation amount should be arranged reasonably for different treatment. (2) Compared with those at low temperature, the dissolved amount of gypsum at high temperature was increased by 1.47-1.50 times, the release amount of exchangeable sodium was in- creased by 2.98-4.70 times, and the release amount of exchangeable magnesium was increased by 2.07-2.90 times. In overall, the improving efficiency of gypsum in summer was better. However, gypsum had two shortcomings in summer. First, a large amount of gypsum leaked away. Second, a large amount of exchangeable magnesium, along with exchangeable sodium, was substituted by gypsum. (3) Compared with the other two treatments, treatment B (mixing gypsum and top 20- cm soil) showed the best improving efficiency, and it was characterized by stepwise dealkalization from top to down. In addition, mixing gypsum and topsoil is more practical in the production. 展开更多
关键词 gypsum Alkali soil improvement IRRIGATION Application pattern Temper-ature
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Study on Performance Regulation and Mechanism of Quicklime and Biopolymer on Hemihydrate Phosphogypsum 被引量:1
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作者 Zaibo Zhou Juanhong Liu +2 位作者 Kun Luo Aixiang Wu Hongjiang Wang 《Journal of Renewable Materials》 SCIE EI 2022年第2期373-384,共12页
In order to reduce the influence of impurities in hemihydrate phosphogypsum(HPG)on the environment and improve the workability of HPG,the effects of the content of quicklime and types of biopolymer(hydroxypropyl methy... In order to reduce the influence of impurities in hemihydrate phosphogypsum(HPG)on the environment and improve the workability of HPG,the effects of the content of quicklime and types of biopolymer(hydroxypropyl methylcellulose,xanthan gum,sodium polyacrylate(PAANa))on the compressive strength,softening coefficient and ultrasonic velocity of HPG were evaluated.When the content of quicklime was 1.5%and the content of PAA-Na was 0.2%,HPG had the best mechanical properties and workability,its water retention rate can be increased by 5.8%,and unconfined compressive strength of 3 days increased by 10.3%and 7 days increased by 13.1%.Through the analysis of scanning electron microscope and X-ray diffraction,it was found that the hydration reac-tion of HPG was more sufficient,the pores size and number decreased,the number of impurities on the crystal surface decreased obviously,and CaF2 and other substances were formed by the reaction after the addition of quicklime.After adding quicklime and PAANa,the indicators of gypsum self-leveling mortar prepared by HPG meet the requirements of the standard. 展开更多
关键词 Hemihydrate phosphogypsum QUICKLIME BIOPOLYMER mechanical properties WORKABILITY gypsum self-leveling mortar
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Modification of FGD gypsum in hydrothermal mixed salt solution 被引量:21
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作者 WU Xiao-qin WU Zhong-biao 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2006年第1期170-175,共6页
A novel utilization way of the sludge from wet calcium-based flue gas desulfurization (FGD) processes has been developed in this paper. This study focused on the conversion of the FGD gypsum into α-hemihydrate calc... A novel utilization way of the sludge from wet calcium-based flue gas desulfurization (FGD) processes has been developed in this paper. This study focused on the conversion of the FGD gypsum into α-hemihydrate calcium sulfate by a hydrothermal salt solution method at atmospheric pressure. Experimental study has been carried out in a batch reactor. Qualitative and quantitative analyses were made by DSC/TG thermal analysis, SEM, XRD, metalloscope and chemical analysis. The experimental results showed that the modification of FGD gypsum was controlled by the dissolution and recrystallization mechanisms. With the introduction of FGD gypsum the salt solution was supersaturated, then crystal nucleus of α-hemihydrate calcium sulfate were produced in the solution. With the submicroscopic structure of FGD gypsum crystal changed, the crystal nucleus grew up into α-hemihydrate calcium sulfate crystals. Thus ,the modification of FGD gypsum was fulfilled. 展开更多
关键词 FGD gypsum MODIFICATION hydrothermal mixed salt solution atmospheric pressure
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Experimental study on cracking behaviour of moulded gypsum containing two non-parallel overlapping flaws under uniaxial compression 被引量:10
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作者 Lekan Olatayo Afolagboye Jianming He Sijing Wang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2017年第2期394-405,共12页
Failure of rock mass that is subjected to compressive loads occurs from initiation, propagation, and linkage of new cracks from preexisting fissures. Our research investigates the cracking behaviour and coalescence pr... Failure of rock mass that is subjected to compressive loads occurs from initiation, propagation, and linkage of new cracks from preexisting fissures. Our research investigates the cracking behaviour and coalescence process in a brittle material with two non-parallel overlapping flaws using a high-speed camera. The coalescence tensile crack and tensile wing cracks were the first cracks to occur from the preexisting flaws. The initiation stresses of the primary cracks at the two tips of each flaw were simultaneous and decreased with reduced flaw inclination angle. The following types of coalescence cracks were identified between the flaws: primary tensile coalescence crack, tensile crack linkage, shear crack linkage, mixed tensile-shear crack, and indirect crack coalescence. Coalescence through tensile linkage occurred mostly at pre-peak stress. In contrast, coalescence through shear or mixed tensile-shear cracks occurred at higher stress. Overall, this study indicates that the geometry of preexisting flaws affect crack initiation and coalescence behaviour. 展开更多
关键词 Crack coalescence Moulded gypsum Non-parallel flaws Primary cracks Uniaxial compression test
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Transformation of Flue-Gas-Desulfurization Gypsum to α-Hemihydrated Gypsum in Salt Solution at Atmospheric Pressure 被引量:18
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作者 吴晓琴 童仕唐 +1 位作者 官宝红 吴忠标 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2011年第2期349-355,共7页
Direct phase transformation of flue gas desulfurization gypsum in hot salt solution at atmospheric pres-sure was investigated.The effects of temperature,salt species,salt concentration,solids content,pH and modifier w... Direct phase transformation of flue gas desulfurization gypsum in hot salt solution at atmospheric pres-sure was investigated.The effects of temperature,salt species,salt concentration,solids content,pH and modifier were examined.The crystals obtained under different conditions and solubility of calcium sulfate in contact with solid gypsum were also determined.α-Calcium sulfate hemihydrate crystals of stubby columnar shape and regular pentahedral sides were obtained under the following conditions:salt concentration 20%-30%,operation tempera-ture 95-100 °C,solids mass content in the slurry 10%-30% and neutral pH.Thermodynamic analysis revealed that phase transformation of calcium sulfate dihydrate to α-calcium sulfate hemihydrate occurs because of the difference in solubilities between the two solid gypsum phases in this system. 展开更多
关键词 flue gas desulfurization gypsum crystal growth thermogravimetric analysis phase transformation
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Fertility and biochemical activity in sodic soils 17 years after reclamation with flue gas desulfurization gypsum 被引量:11
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作者 ZHAO Yong-gan WANG Shu-juan +3 位作者 LIU Jia ZHUO Yu-qun LI Yan ZHANG Wen-chao 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2021年第12期3312-3322,共11页
Previous studies have mainly focused on changes in soil physical and chemical properties to evaluate the reclamation of sodic soils using flue gas desulfurization(FGD)gypsum.However,information on the effects of this ... Previous studies have mainly focused on changes in soil physical and chemical properties to evaluate the reclamation of sodic soils using flue gas desulfurization(FGD)gypsum.However,information on the effects of this reclamation method on microbial-based indicators of soil quality is limited,particularly after many years of FGD gypsum application.This study aimed to investigate the long-term effects of FGD gypsum on soil organic carbon(SOC),nutrients,microbial biomass and enzyme activity.Data were collected from soils of three exchangeable sodium percentage(ESP)classes(i.e.,low-,middle-and hjgh-ESP classes of 6.1-20,20-30 and 30-78.4%,respectively)17 years after FGD gypsum treatment in Inner Mongolia,China.Averaged across the three ESP classes,FGD gypsum application increased the SOC contents at the 0-20 and 20-40-cm soil depths by 18 and 35%,respectively,and increased available potassium at the 0-20-cm soil depth by 51%compared with the no-gypsum controls.The microbial biomass carbon and microbial biomass nitrogen contents at the 20-40-cm soil depth increased by 69 and 194%,respectively,under FGD gypsum.Except in the high-ESP class,urease activities in the 0-40 cm soil profile were significantly higher in the FGD gypsum treatments than in the controls.A significant increase in alkaline phosphatase activity was concentrated in the 20-40 cm soil layer;few classes showed significant increases in catalase and invertase activities in the 0-20 cm soil layer.Pearson correlation analysis showed that increases in soil fertility and biological activity could be attributed to reductions in electrical conductivity,pH and ESP caused by FGD gypsum application.These results confirm that FGD gypsum application is a viable strategy for reclaiming sodic soils due to its positive effects on soil fertility and biochemistry and that it may contribute to soil ecosystem sustainability. 展开更多
关键词 gypsum organic carbon nutrient pools microbial biomass enzyme activity
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