Calcium Sulfate Solution Research Articles

Effects of sodium and calcium sulphates on volume stability and strength of lime-stabilized kaolinite

Lime treatment of sulphate-bearing clay soils has been shown to adversely affect their properties. In the current work, the effects of soaking untreated and lime-stabilized kaolinite samples in water and sodium and calcium sulphate on swelling and unconfined compressive strength are investigated and compared. Specimens were treated with 1, 3, or 5% lime and cured at 35 °C for 1, 7, or 28 days, followed by soaking in water or 10,000 ppm sodium or calcium sulphate solutions. The results show that soaking lime-treated kaolinite samples in sodium and calcium sulphate solutions promotes swelling, which is greatly influenced by the length of the curing period. Swelling is the result of the formation of ettringite with high affinity for water absorption, which results in a reduction in unconfined compressive strength. Ettringite forms in environments with high pH and active sulphates as small crystals which destroy the structure of stabilized soils due to expansion, particularly at the early stages of formation, given its high affinity for water absorption. SEM micrographs show ettringite crystals growing on and between clay particles.

In Situ Transmission Electron Microscopy Explores a New Nanoscale Pathway for Direct Gypsum Formation in Aqueous Solution

In the modern construction industry, large gypsum (CaSO4·2H2O) boards are manufactured through a two-step procedure, which features the heating of fine gypsum powders to form the intermediate plaster of Paris (bassanite, CaSO4·0.5H2O) followed by hydration of the intermediate phase to form the final formed product. Here, we explore a novel pathway toward the fabrication of gypsum microneedles that bypasses formation of the intermediate bassanite phase. Using in situ liquid transmission electron microscopy, the dynamic behavior of fine gypsum powders in a calcium sulfate solution is investigated at the nanoscale and in real time. An oriented-attachment mechanism is found to dominate the direct transformation of gypsum nanoparticles to gypsum microneedles, where no intermediate phases are involved. Our experimental results advance the fundamental understanding of the dynamic interactions between gypsum and water. The proposed nanoscale pathway for gypsum evolution could potentially revolutionize the construction industry rooted in gypsum board manufacturing by promising a time- and energy-efficient mass production procedure. In addition, this work can inspire research efforts associated with geology, archeology, and biology, where historical significance is frequently deduced from gypsum-related discoveries.

The source of sulfur in sulfide deposits in the Siberian Platform traps (from isotope data)

The source of sulfur in giant Norilsk-type sulfide deposits is discussed. A review of the state of the problem and a critical analysis of existing hypotheses are made. The distribution of δ34S in sulfides of ore occurrences and small and large deposits and in normal sedimentary, metamorphogenic, and hypogene sulfates is considered. A large number of new δ34S data for sulfides and sulfates in various deposits, volcanic and terrigenous rocks, coals, graphites, and metasomatites are presented. The main attention is focused on the objects of the Norilsk and Kureika ore districts. The δ34S value varies from -14 to +22.5‰ in sulfides of rocks and ores and from 15.3 to 33‰ in anhydrites. In sulfide-sulfate intergrowths and assemblages, δ34S is within 4.2-14.6‰ in sulfides and within 15.3-21.3‰ in anhydrites. The most isotopically heavy sulfur was found in pyrrhotite veins in basalts (δ34S = 21.6‰), in sulfate veins cutting dolomites (δ34S = 33‰), and in subsidence caldera sulfates in basalts (δ34S = 23.2-25.2‰). Sulfide ores of the Tsentral’naya Shilki intrusion have a heavy sulfur isotope composition (δ34S = +17.7‰ (n = 15)). Thermobarogeochemical studies of anhydrites have revealed inclusions of different types with homogenization temperatures ranging from 685 °C to 80 °C. Metamorphogenic and hypogene anhydrites are associated with a carbonaceous substance, and hypogene anhydrites have inclusions of chloride-containing salt melts. We assume that sulfur in the trap sulfide deposits was introduced with sulfates of sedimentary rocks (δ34S = 22-24‰). No assimilation of sulfates by basaltic melt took place. The sedimentary anhydrites were “steamed” by hydrocarbons, which led to sulfate reduction and δ34S fractionation. As a result, isotopically light sulfur accumulated in sulfides and hydrogen sulfide, isotopically heavy sulfur was removed by aqueous calcium sulfate solution, and “residual” metamorphogenic anhydrite acquired a lighter sulfur isotope composition as compared with the sedimentary one. The wide variations in δ34S in sulfides and sulfates are due to changes in the physicochemical parameters of the ore-forming system (first of all, temperature and Pch4) during the sulfate reduction. The regional hydrocarbon resources were sufficient for large-scale ore formation.

The isotopic record of gypsum diagenesis in diluted solutions: Observations in natural salinas and experiments

Gypsum deposits are often considered as reliable components of evaporitic series for reconstructing their conditions of precipitation from saturated (marine or non-marine) calcium-sulfate solutions. The isotopic compositions of the hydration water and of the sulfate are thought to provide the composition and thus the origin of the parent solution, assuming that the primary signals are preserved. The present study demonstrates that dissolution-recrystallization of gypsum from natural salinas and in experiments where gypsum reacted with diluted solutions, was responsible for the rapid modification of the primary isotopic signal by the incorporation of the reacting water in the crystal lattice of the new gypsum generation. It is also shown that gypsum diagenesis may cause significant changes of the isotopic composition of the sulfate due to fractionation between the resulting dissolved and new gypsum phases.

Modeling of Nucleation Rate of Supersaturated Calcium Sulfate Solutions.

Reverse osmosis treatment of the Central Arizona Project (CAP) water provokes scaling because of its high content in salt. Experiments simulating various solutions of calcium sulfate (CaSO4) made by mixing of sodium sulfate (Na2SO4) and calcium chloride (CaCl2) reinforced this idea. An increase of the degree of supersaturation of the solution from 8.67 to 42.08 decreased the induction time for precipitation of calcium sulfate solutions. The use of Flocon® 135 as antiscalant increased the induction time. The increase was directly related to the concentration of antiscalant. Working with 11.06 degree of supersaturation, a dose 0 ppm of antiscalant has an induction time of 217 minutes. A dose of 0.5 ppm of Flocon 135 inhibits completely the crystal growth in solution. The use of 21.07 degree of supersaturation showed an induction time of 36 minutes for 0 ppm of antiscalant, 78 minutes for 0.25 ppm of antiscalant, 91 minutes for 0.5 ppm of antiscalant, 119 minutes for 0.75 ppm of antiscalant, 139 minutes for 1 ppm of antiscalant, 243 minutes for 1.25 ppm of antiscalant, and crystal growth and nucleation rate are completely inhibited by use from 2 ppm or more of antiscalant. The use of a solution of 42.08 degree of supersaturation gave the following results: 11 minutes to nucleation for 0 ppm of antiscalant, 19 minutes for 0.5 ppm of antiscalant, 24 minutes for 1 ppm of antiscalant, 36 minutes for 1.5 ppm of antiscalant, 84 minutes for 2 ppm of antiscalant, and 123 minutes for 2.5 ppm of antiscalant. The nucleation rate was 2.1 × 109 nuclei/cm3.min for 8.67 degree of supersaturation to 1.26 × 1027 nuclei/cm3.min for 42.06 degree of supersaturation. Logarithmic plots of the induction time (tind ) as function of 1/[ln(S)]2 for calcium sulfate without and with addition of antiscalant for fixed temperature provides a linear trend with slope B as a constant proportional to the surface tension and molar volume. Modeling of the nucleation rate allows predicting the induction time by knowing a unique constant value (C=22.86) associated to each nucleation rate (from 5.05 × 1011 to 1.22 × 1028). Each nucleation rate values are related to a specific degree of supersaturation (from 8.67 to 42.06) by this equation:

Analysis of the onset of calcium sulfate scaling on RO membranes

Inhibition of the formation of an initial scale layer is the key measure for scale prevention. Major efforts are therefore focused on understanding the complex processes involved in the inception of scaling on reverse osmosis membranes. The objective of this research was to elucidate phenomena involved in the development of the initial scale layer from a supersaturated solution of calcium sulfate by dual measurements of the flux decline and frictional pressure drop. A single parameter model describing surface coverage of the membrane by lateral crystal growth of initial particles was found to give an excellent fit to experimental flux decline data. The source of the initial particles is, as generally accepted, by membrane surface nucleation and/or by deposition from small particles existing in the bulk. Frictional pressure drop measurements clarify some roughness features of deposits. In the absence of anti-scalants scale deposits from solutions of different supersaturations have similar roughness morphologies whereas, morphological changes, induced by the anti-scalants result in higher roughness heights.

Enhanced Heat Transfer and Fouling Propensity of Diamond-Like Carbon Coated Smooth and Finned Tubes During External Nucleate Boiling

Smooth DLC (diamond-like carbon) coated surfaces can profoundly mitigate scaling during pool boiling of calcium sulphate solutions. Previous investigations though carried out mostly for the smooth surfaces rather than structured, i.e., finned tubes. This study compares experimental results of DLC coated smooth and finned tubes at clean and fouling conditions. Fouling runs were conducted during pool boiling of saturated CaSO4 solution of 1.6 g/L at 300 kW/m2. The substrate of the attempted tubes was stainless steel and finned tubes of 19 and 40 fins per inch were used. The DLC coated smooth tube showed an enhanced clean heat transfer up to 50% and reduced fouling resistance compared to the uncoated smooth tube. After a short operating time, though, the coated smooth tube reached an asymptotic fouling resistance of 0.00005 m2 K/W whereas for the uncoated smooth tube, it was 4.8 times higher. DLC coating of the finned tubes with the physical vapor deposition (PVD) technique implicated difficulties. The base surface of the finned tubes was defectively coated. The defectiveness of the coating was attributed to the limitation of the PVD for coating of structured surfaces.

Unraveling the Sulfate Sources of (Giant) Gypsum Crystals Using Gypsum Isotope Fractionation Factors

We combine newly determined isotope fractionation factors of gypsum precipitated in the laboratory with the isotopic compositions of natural anhydrite and gypsum to unravel the sulfate sources of the giant selenite crystals in the Naica mine (Chihuahua, Mexico). Gypsum was precipitated in the laboratory from CaSO4-NaCl-H2O solutions across a broad temperature range to establish the isotopic fractionation behavior of the sulfate molecule between the solid and dissolved phase. Oxygen isotopes show a significant fractionation dependence on temperature, with the solid phase more depleted in light isotopes with decreasing temperature. Sulfur isotopes display only a weak but similar dependence on temperature. At high salinity (4.5 M NaCl) no temperature dependence was found for the isotope composition. Based on this fractionation behavior, we attempt to elucidate the origin of the sulfate source(s) responsible for the formation of the (giant) gypsum crystals in the Naica mine. Detailed analysis of the isotopic composition of anhydrite, gypsum, and water samples strongly suggests that different types of anhydrite (of hypogenic and sedimentary origin) were dissolved to form these unique gypsum formations. The homogeneous isotopic composition of most gypsum crystals analyzed reveals an effective hydrodynamic mixing and a slow kinetics of precipitation fed by solutions of calcium sulfate from different anhydrite sources.

Experiments on Integral and Local Crystallization Fouling Resistances in a Double-Pipe Heat Exchanger With Wire Matrix Inserts

Wire matrix inserts are used in different applications of tubular heat exchangers to improve tube side heat transfer. They have also been used to suppress fouling in crude oil refining services. In this paper it is investigated whether the changed hydrodynamic and thermal conditions when applying wire matrix inserts have an impact on crystallization fouling compared to the plain tube. With a turbulent flow, at Reynolds number of 9877 and an inlet temperature of 42°C, fouling tests with an aqueous calcium sulfate solution for two wire matrix inserts with a different packing density were carried out and compared with a plain tube. Integral and local measurements of the fouling were performed. The experiments were realized in a double-pipe heat exchanger with a pipe length of 2000 mm. The integral fouling resistances between the inserts and the plain tube showed no significant difference, whereas major differences of the local fouling resistances were observed. Compared to the plain tube, the inserts showed an increased heat transfer up to a maximum of 35% but also a significantly increased pressure drop. Fouling on the inserts themselves, which was observed optically, is the possible explanation for this behavior.

Statistical Analysis of Salt Deposition inside PEFC GDL from X-Ray Tomography

X-ray Computed Tomography (XCT) has been utilized extensively in the past decade to examine the internal features of PEMFC components, including extensive examination of the GDL structure [1-3]. Through the use of optics, micro-scale (and nano-scale) resolution has been achieved allowing for investigation of GDL’s, MPL’s and MEA’s for both in-situ [2] and ex-situ[1,3] studies without the need to cut into and damage the sample to obtain internal views. Published research with respect to GDL’s has produced information ranging from porosity distributions [1] and transport properties[3] to liquid water distribution inside the pores [2,3]. This study examines the salt deposition within a PEMFC cathode GDL using micro-XCT. The GDL in question came from a cell which was run on air that contained a calcium sulfate impurity[4]. Following a break-in period of 24 hours, a nebulizer was used to inject calcium sulfate solution (in DI water) at a 5 ppm concentration (based on dry air flow rate) into the cathode air stream. Galvanostatic performance data was recorded at 200mA/cm2, which showed a steady voltage loss rate more than 10 times compared to a non-contaminated baseline cell. During this time, salt deposits began to build up within the GDL and flow channels. This salt build up, combined with ionic conductivity changes in the CCL and changes in flooding behavior eventually led to the end of the experiment, because the cell was unable to hold the 200mA/cm2 [4]. Following the experiment, the cell was disassembled and components separated. At this time, the salt build up on the GDL surface and on the gas flow channels was visually observed to block the air flow pathways. Tomographies of the salt deposited GDL were obtained in three regions: a) near the inlet b) near the center c) and near the outlet. The resulting tomographies are provided in the 3D images presented in Figure 1. These tomographs show the different deposition patterns through the cell. Near the inlet, where the highest amount of water is produced, salt deposition appears to be uniformly distributed with no preferential nucleation site. Alternatively, near the center and the exit of the cell, the salt deposits in and on the GDL follow a distinct precipitation pattern, which are characterized by salt deposits with a crystalline structure that have the potential to grow out of the GDL. These deposits were observed as the flow channel obstructions that contributed to the end of the experiment. Through close examination of the 3D reconstruction (and shown in Figure 1), it is seen that in the center and exit regions of the GDL, most of the salt deposition appears to be flush with the GDL surface, which indicates that salt precipitates appear to be restricted from growing in that direction (out of the GDL), which provides evidence that salts nucleate under the lands (ribs). These salt crystals then have the ability to grow in the in-plane direction and out from under the lands (ribs) where salts can grow unrestricted out of the GDL and into the flow channel grooves. This process is in good agreement with the conclusions presented by Wang et al.[4], that low water concentrations under the flow channel ribs precipitates the formation of salt deposits. Statistical analysis is performed on the exported salt deposited GDL tomographs to examine the changes in void space (porosity) within the GDL in the through-plane direction. As salts appear to nucleate under the lands, this examination of the deposition profiles is presented for both regions of salt build up under the grooves and under the lands (ribs). These results are extended to comment on the changes to porosity under cell compression. Finally, we examine the effect of salt contaminant concentration and cell operating current on the salt precipitation patterns.

The effect of pressure on the kinetics of γ-anhydrite crystallization investigated by diamond anvil cell

The crystallization kinetics of γ-anhydrite was investigated in the temperature and pressure ranges of 373–473K and 1094–1903MPa using a hydrothermal diamond anvil cell (HDAC) and Raman spectroscopy. A calcium sulfate solution was formed by dissolving gypsum in water at high pressure, and γ-anhydrite crystallized due to the increasing temperature. The relationship among the reaction rate, k, the temperature, T, and the pressure, P was established as k=−1.75×10−3+1.83×10−6P+3.57×10−7T, with an R2 value of 0.943, of which the applicable range is 373K≤T≤473K and 1196MPa≤P≤1903MPa. An elevation of T or P will accelerate the crystallization rate of γ-anhydrite. The time exponent n obtained between 0.96 and 1.29 indicates that the process of crystallization should be controlled by instant nucleation on the grain boundary and diffusion controlled growth. In the process of crystallization, the volume is reduced because of the decrease of pressure, and the volume change ΔV is equal to −6.05×10−6m3/mol. The calculated activation energy Ea is 10.7kJ/mol, and the pre-exponential factor A is 2.27×10−2s−1.

Мodernization of Conventional Spiral Wound Channel - A Tool to Escape Fouling, Expand Membrane Life and Increase Recovery

The survey shows that high operational costs of membrane facilities and large amounts of concentrate effluents are mainly attributed to fouling and scaling. The research of scaling and fouling mechanisms shows that these processes depend not only on hydrodynamic factors, but on membrane type and channel geometry. However, the main disadvantages of the modern RO techniques are connected with membrane fouling, concentrate flow, and complicated design. The main ways to develop new fouling-free techniques are outlined and suggest a new concept of modified "open-channel" spiral wound membranes. Successful attempts were undertaken by the author to modify spiral wound membrane channels to limit fouling and scaling potentials of membrane modules. Elimination of spacer mesh from the feed channels eliminates "dead" regions that provide scaling and fouling conditions whilst also reducing the risk of particle "trapping" and associated dramatic cross flow resistance increase. High recoveries could also be reached due to strong stability of calcium carbonate and sulphate solutions. Introduction of a new "open-channel" configuration offers new perspectives to escape fouling and develop a novel technique to treat water with high fouling and scaling potential. This novel concept of spiral wound module with an "open channel" design has been developed, field-tested and introduced into practice. A test procedure is described that enables us to compare fouling propensities of RO facilities tailored with different membrane types and channel configurations. Cross-flow resistance increase, scaling, and fouling rates and flux decrease are predicted for different feed water compositions. Introduction of new "open channel" spiral wound module into desalination practice enables us to considerately expand the application area of RO techniques.

Ca2+ as an Air Impurity in Polymer Electrolyte Membrane Fuel Cells

Cationic contamination is known to cause performance degradation and reduced lifetime in polymer electrolyte based electrochemical systems. Calcium is an important cationic impurity due to its prevalence in roadside particulates and as an airborne contaminant. The role of calcium ion (Ca2+) is investigated in-situ by injecting a solution of calcium sulfate (CaSO4) in deionized (DI) water into the cathode of a polymer electrolyte membrane (PEM) fuel cell through a nebulizer. Stability tests are conducted to determine the effects at various current densities with various Ca2+ concentrations. It is found that 5 parts per million (ppm, molar ratio) eq. Ca2+ in air is sufficient to lead to high cell performance loss at 1 A/cm2 as well as severe membrane degradation. Precipitation of CaSO4 is found at the contact regions between the gas diffusion layers (GDL) and bipolar plates of the cathode at all test conditions. The amount of precipitation becomes sufficient to cause mass transport issues.

Experimental Measurement of Induction Period of Gypsum Precipitation in the Laminar Flow State

The gypsum precipitation was investigated under different conditions of temperature and supersaturation, which has significant effects on the optimization of humidification-dehumidification process. The spectrophotometer was used to measure the precipitation induction period of gypsum. The primary nucleation of calcium sulphate solution was investigated with the combination of nucleation induction period and classical nucleation theory. It was found that a power relation existed between the induction period and the operation conditions.

Effect of Ca2+ as an Air Impurity on Polymer Electrolyte Fuel Cells

Cationic contamination is a well-known phenomenon that causes performance degradation and decrease in lifetime in polymer electrolyte based electrochemical systems. Calcium is a significant cationic impurity due to its prevalence. In this work, the role of calcium is investigated in-situ by injecting into the cathode of a single polymer electrolyte fuel cell (PEFC) through a nebulizer as a solution of calcium sulphate (CaSO4) in deionized (DI) water. Stability tests are conducted to determine the contaminant effects at different current densities with different Ca2+ concentrations. It is found that 5 ppm Ca2+ in air at 1 A/cm2 is high enough to lead to high cell performance loss as well as severe membrane degradation. Chemical precipitation is found at the contact regions between the gas diffusion layer (GDL) and flow plate of the cathode at all test conditions.

PHYSICAL AND CHEMICAL RESEARCH OF PROCESSES OF SALT FORMATION IN THE WATER OF BALKHASH LAKE

In recent years about 5.04 million tons of salts a year arrive down the River Ili to Balkhash Lake. Using water of the Ili River for filling the Kapchagaisky reservoirreduced volume of arriving water from the river to 2/3 and decreased level of the lake. It causes mineralization, which advances forecasts. Complex research of influence of the IliRiver on the current state of salt formation in Balkhash Lake is needed as well as hydrochemical research of the water area of Balkhash Lake and the Ili River. In our study the chemical analysis of the qualitative and quantitative characteristics of water with use of classical and physical and chemical methods of the analysis, such as, nuclear and absorbing, roentgen fluоrescence spectrometry and crystal and optical analysis was realized. It is established that crystallization of salts begins with calcium carbonate in the form of aragonite, crystals of nesquehonite join this process, and in deposit the main carbonate of magnesium drops out. Processes of metamorfization with participation of ions of carbonate, hydro carbonate and calcium, are bringing calcite sedimentation. They occur everywhere, but processes with participation of magnesium ions are bringing magnesite or dolomite sedimentation only in extreme east stretch of the lake. In saturated solutions of carbonates there is an increase in ions of potassium in sediment. Thus, their quantities increase a little. It is especially sharp for sulfate and sodium chloride in the direction from the west to the east. The calcium carbonate in the firm phase possesses more absorbing ability, than magnesium carbonate, and the presence of ions of potassium at sediment doesn't change structure of the last. At isothermal evaporation of mix of solutions of potassium carbonate with saturated solution of calcium carbonate, and also potassium sulfate with saturated solution of calcium sulfate and the joint sedimentation of potassium is noticed.

Calcium sulfate precipitation studies with scale inhibitors for reverse osmosis desalination

This study is focused on precipitation and inhibition studies of calcium sulfate (gypsum) scale in reverse osmosis (RO) desalination plants. The temperature and concentration range encountered in brackish water RO desalination process has been considered in conducting precipitation and inhibition experiments. Initial screening of a number of additives has been carried out. Formation of gypsum scale has been verified by XRD and SEM analysis. Successful additives were evaluated by measuring induction times using conductivity of solutions and their performance was compared with that of blank supersaturated calcium sulfate solution. The induction time of STD100, SHMP, STD101 was found to be 70, 690 and 1200min respectively at dose level of 10ppm, whereas a blended formulation FM101 (10ppm) did not show any precipitation till 3000min. The SEM micrographs of precipitate collected when FM101 was added as a scale inhibitor with that of a blank solution and other inhibitors indicate that, the formulation FM101 has significantly modified the crystal morphology and is probably responsible for increased induction time.

ACID CLEANING OF GYPSUM DEPOSITS FROM A HEAT TRANSFER SURFACE

Scale deposits formed from supersaturated calcium sulfate solutions with and without mitigating wood pulp fibers where successfully removed from a stainless steel heat exchanger test section in a separate flow recycle loop with dilute acetic acid. The calcium ion concentration was lower in the cleaning solution when fibers were added to the fouling suspension in the fouling experiments. The calcium ion concentration was lowered further in the cleaning solution when higher fiber concentrations were used in the fouling solution. This confirmed that fibers modified the nature and structure of the deposit and reduced the amount of fouling. When low concentrations of fiber were used (<0.1 mass percent), the corresponding decreased rate of cleaning indicated that some of the foulant had been trapped in the cellulosic structure adhering to the surface, leaving less deposition on the actual metal surface.

Fouling mitigation of heat exchangers with natural fibres

Fouling mitigation research has been extended to investigate the effects of fibre concentration, fibre length, and fibre flexibility, on heat transfer fouling with supersaturated calcium sulphate solutions. Two long-fibre softwood pulp fibres (pine and spruce) of similar mean length but different fibre flexibility were used as well as a short-fibre, hardwood eucalypt pulp. Fouling was prevented altogether with a 0.25% suspension concentration of long-fibre pine fibres for more than 46 days, and for 38 days with a 0.1% suspension of short-fibre. At 0.05%, concentration, the onset of fouling was delayed for 14.5 days with the short-fibre hardwood pulp. The final asymptotic level of fouling was about 30% of the fibre-free fouling solution. The shorter-fibre hardwood pulp fibres are more effective than either of the long-fibre softwood pulps at the same concentration of 0.05% (higher population). Fouling started at about 1.8 days for both long fibre pulps at 0.05% concentration, and heat transfer augmentation was still achieved in the induction period. Stiffer pine fibres were more effective at fouling mitigation than the more flexible spruce fibres. An equal percentage mixture of hardwood and pine pulp at 0.05% concentration also showed that the shorter hardwood fibres are more effective in mitigating fouling.

Aqueous calcium sulphate as bone graft for voids following open curettage of bone tumours

Reported strategies for void filling in bone include autograft, allograft, synthetic bone substitutes or various combinations of these materials, but poor response rates and donor morbidity have created a desire to find a better option. Calcium sulphate as a stand-alone graft material reconstruct bone following curettage has not been previously reported. The purpose of this study was to assess the efficacy and radiological quality of healing, the time to healing, the functional outcomes and the complications following curettage and grafting using an injectable aqueous calcium sulphate (BonePlast; Biomet, Warsaw, IN, USA) as the sole grafting strategy. The procedure of curettage and grafting with an aqueous solution of calcium sulphate was undertaken. The patients were regularly reviewed clinically and radiologically for a minimum of 12 months (range: 12-85 months). Forty-six procedures in 46 patients were reviewed. Radiological outcomes of healing were established and functional outcomes were obtained from each patient at annual follow-up review. A complete response was seen in 38 patients (83%) at a median of 6 months following the procedure (range: 1-24 months). Seven patients (15%) displayed only a partial response after a median of 13 months post-surgery (range: 12-53 months). There was one non-response to treatment (2%) after 40 months of follow-up. The mean functional score was 99%. Aqueous calcium sulphate as a sole grafting agent for void management after curettage simplifies current treatment practices and displays good bone reconstruction in a comparatively short time frame, with excellent functional results and acceptable complication rates in the setting of tumour surgery.