Granulated Powder Research Articles

Eco-friendly stabilization of highway lateritic soil with cow bone powder admixed lime and plastic granules reinforcement

Modernization, industrialization and rapid changes in the modern lifestyle have resulted in massive waste materials in the environment. Scientists are continuously evolving innovative ways for efficient reuse/recycling and the safe disposal of waste materials. This study explores potential waste materials reuse in additive stabilization of a fair to poor highway lateritic soil (clay with low plasticity/silty clay) as a sub-base material and the impact of such additives in reducing the lime content during soil stabilization treatment. Soil samples obtained from road construction burrow pit in Ado-Ekiti, south-west, Nigeria were classified as CL group (clay with low plasticity), according to the Unified Soil Classification System (USCS) and A-6 material (silty clay) which is fairly poor highway material. Hydrated lime, Cow bone and plastic wastes were also locally sourced. Geotechnical tests (Compaction, Unconfined Compressive Strength test, direct shear and consolidation test) were carried out on the control and stabilized samples according to BS 1990. The results of the Unconfined Compressive Strength tests revealed that the 90 % lateritic soil +10 % lime and a combination of 6 % lime +7 % cow bone powder +1 % plastic waste (6 % L +7 % CBP + 1.0 %PP) mixes produced the best result for the lime stabilized and waste-lime stabilized soil samples, respectively. The direct shear tests, indicated a reduction in the soil’s cohesion (c) from 38 kN/m 2 to 28 kN/m 2 and an improvement in the angle of internal friction ( ϕ ) from 29º to 45º for the optimum waste-lime mix. 10 % lime (L 10 ) sample recorded comparatively lower c and ϕ values of 33 kN/m 2 and 41º, respectively. The mix (6 % L +7 % CBP + 1.0 % PP) had improved the unsoaked and soaked CBR of 61.7 % and 37.6 %, respectively compared to the lime stabilized soil which recorded lower values of 57.8 % and 31.3 %, respectively. The permeability of the soil was reduced from 3.22e-03 cm/s to 9.12e-04 cm/s on the application of 10 % lime however the waste-lime optimal mix produced a lower value of 5.26e-04 cm/s. The results of the consolidation tests also revealed that the 6 % L +7 % CBP +1.0 % PP sample had a lower coefficient of volume compressibility (Mv) of 1.065e-04 m 2 /kN than the untreated samples which is 1.365e-04 m 2 /kN implying the stabilized mix is less susceptible to compressibility than the untreated samples. The durability results revealed that the sample recorded a strength of 201.7 kPa after being subjected to 3 wet-dry (w-d) cycles for 6 % L +7 % CBP +1.0 % PP sample, while the 10 % lime stabilized soil was found to have a strength of 148.5 kPa strength. Based on the findings, it can be concluded that the 6 % L +7 % CBP +1.0 % PP mix performed better than the 10 % lime stabilized mix with the waste materials substituting for 4 % of the lime and producing better results in terms of suitability as a highway sub-base material. • The partial replacement of lime improved weak highway lateritic soils. • Waste materials (cow bone powder and plastic granules) were suitably reused. • Near-zero emissions processing of stabilization additives was achieved. • Cleaner and energy-saving methods were employed for the disposal of waste. • Reduced weather sensitivity and compressibility were achieved for the soil mixture.

Hydroxyurea granules for the management of sickle cell disease in children

BackgroundMany studies have demonstrated the effectiveness of hydroxyurea in the management of sickle cell disease. The drug, which is an antimetabolite initially developed for the treatment of myeloproliferative disorders has been repurposed, even though its use for the initial indication has been retained. Currently, in most developing countries the only available dosage form is the 500 mg capsule. Pediatric hydroxyurea formulations are yet to appear on many markets, thus, patients have to rely on compounding facilities to have their medications extemporaneously prepared for them from the adult solid dosage form. Interestingly, pharmacies that provide compounding services are limited, additionally; most extemporaneously compounded products have very short shelf lives. The aim of this study was to formulate and optimize dry powder granules of hydroxyurea to be reconstituted into an oral suspension in order to prolong the shelf life of the product. MethodTwo different batches of Hydroxyurea granules were formulated using the wet granulation method. Granules were characterized by appearance, pH and drug content. Microbial contamination test was conducted using the pour plate method. ResultsGranules prepared were easy to reconstitute. pH of the suspensions were between 7 and 8. Drug content in formulated granules were 95 and 92% of expected values. No E. coli was found in the suspensions and the total microbial count was less than the USP limits. Granules remained stable over the study period of 60 days. ConclusionDry granules of hydroxyurea can be produced in bulk and packaged into bottles for reconstitution into suspensions by patients. These formulations have better stability than extemporaneously compounded suspensions. Making hydroxyurea granules available for children with sickle cell disease will be a convenient, time and cost effective way of meeting their medical needs.

Influence of strontium hexaaluminate percentage on the structure and properties of alumina-zirconia ceramics

In this paper, alumina-zirconia ceramics with different contents of strontium hexaaluminate are investigated. Materials were obtained by pressing granulated powder and following free sintering. An XRD analysis was carried out. The structure was studied using a scanning electron microscope. Vickers hardness was determined at a load of 10 kg. Fracture toughness was evaluated using the indentation method. The change of composites structure at different temperatures was analyzed. The growth of SrAl12O19 platelet length proceeds predominantly up to 1400 °C. The platelet length range from 0.30 μm to 1 μm. At a temperature of 1500 °C the platelets thickness increases. In materials sintered at 1520 °C for 5 h with an increase in the SrAl12O19 content, the relative density decreases, and the porosity of the materials increases. Increasing the strontium hexaaluminate content in sintered materials decreases the alumina grain size. With strontium hexaaluminate content of 15 wt %, the average grain size of the alumina component decreases by 19% compared to unaided alumina ceramics (from 0.74 ± 0.06 to 0.60 ± 0.04 μm). With increasing SrAl12O19 content, the length of the platelets increased one and a half times from 0.80 μm to 1.20 μm. The width of the platelets remained essentially unchanged. Formation of strontium hexaaluminate platelets in materials and increase of its content contribute to increasing of fracture toughness of alumina-zirconia ceramics. The maximum level of fracture toughness is recorded at 15 wt % strontium hexaaluminate and is 7.7 ± 0.3 MPa*m1/2. The hardness of the composite with 15 wt % SrAl12O19 is 18% lower than alumina zirconia ceramics and is ∼1400 HV. Mechanisms for increasing the fracture toughness of alumina-zirconia ceramics depend on the strontium hexaaluminate content. At hexaaluminate strontium content up to 6 wt %, bending, platelet fracture, and bridging mechanisms are observed. At 9 and 12 wt % SrAl12O19 deflection mechanisms, crack branching and platelets fracture were detected. At 15 wt % SrAl12O19 the crack deflection is observed.

Effects of Gypsum and Limestone Powder on Fresh Properties and Compressive Strength of Concrete Containing Ground Granulated Blast Furnace Slag under Different Curing Temperatures

Usage of industrial by-products such as ground granulated blast furnace slag (GGBFS), gypsum, and limestone powder have gained prominence in concrete production. It is, therefore, very important to conduct research into the various materials and their attendant influence on properties of concrete at different ambient temperatures. This study focused on the slump, setting time, and compressive strength of concrete with GGBFS at a constant replacement ratio, in which different forms of gypsum, namely anhydrous and di-hydrate gypsum, were also added at different SO3 contents. Effect of addition of limestone powder was also investigated. The results of the tests indicated that both gypsum and limestone powder when added to a mix proportion containing GGBFS can improve slump and compressive strength of concrete. Anhydrous gypsum produced higher optimum compressive strength as compared with di-hydrate gypsum. An increase in SO3 content from gypsum contributed to strength development at early ages but reduced its long-term strength. Gypsum added to the mix delayed initial and final setting time. Limestone powder accelerated both initial and final setting times and contributed to increasing compressive strength after one day, thus three to seven days; however, the long-term strength was reduced. Curing temperature of concrete influenced strength development and the time required to remove formwork was determined for different mixtures using “maturity function”.

Synthesis of Submicron, Nanostructured Spherical Powders of Y3Al5O12-Phases by the Method by Ultrasonic Spray Pyrolysis and Investigation of Their Structure and Properties

The results of laboratory studies of the submicron Y3Al5O12 (YAG) phase powders synthesized by ultrasonic spray pyrolysis are presented. A structural-phase analysis of aerosol powders was carried out and an assessment of the tendency of the synthesized powders to sintering was made. The working solution for the aerosol was prepared on the basis of distilled water with aluminum nitrate hexahydrate Al(NO3)3 x 6H2O and yttrium nitrate hexahydrate Y(NO3)3 x 6H2O dissolved in specified proportions. Spherical submicron nonagglomerated powders of Y3Al5O12–phase with a small YAlO3-phase content were synthesized by this method. Powder granules with a diameter of 0.75 microns had a nano-fragmentary polycrystalline structure with an average crystal size of 16 nm. During the sintering of powders with such a unique structure, diffusion mass transfer processes are activated, which contributes to a more efficient compaction of the material. Aerosol powder sintering experiments have shown that the best results are achieved when the process is carried out at 1700 °C for 6 h. As a result, a dense YAG-ceramic material was obtained, the structure of which does not contain residual pores and is characterized by a uniform distribution of equiaxed grains.

Internal interfacial interaction analysis of geopolymer-recycled aggregate pervious concrete based on a infiltration model

The comprehensive utilization of solid waste and construction waste is an important problem at present. In this study, geopolymer paste was prepared by fly ash, ground granulated blast furnace slag powder and the alkali-activator. Then geopolymer recycled-aggregate pervious concrete(GRAPC) was prepared by geopolymer paste and recycled coarse aggregate. The internal interfacial interaction between geopolymer paste and recycled coarse aggregate was studied by theoretical analysis and laboratory tests. The surface texture profile characteristics of recycled coarse aggregate was quantitatively measured by 3D morphometer. Contact angle was tested to characterize the surface energy of geopolymer paste. Combined with the microstructure of the experimental analysis and the classical theory of solid–liquid contact model, the geopolymer paste-recycled aggregate infiltration model was established. The investigation of infiltration and interaction of geopolymer paste on different types of recycled coarse aggregate was carried out. Based on the measurement of paste thickness and GRAPC macro performance, the actual internal interfacial interaction of GRAPC was analyzed by the infiltration model. The paste thickness, working performance, mechanical properties and water permeability of GRAPC were analyzed by laboratory tests. Furthermore, the correlation laws of porosity and enhanced treatment of recycled coarse aggregate were analyzed by the systematical investigation on internal interaction of GRAPC.

Fluidized Bed Processing: Versatile Technique in Dosage form Development

Fluidized bed processor is the popular and successful technique widely being in pharmaceutical industries. Fluidized bed processor was developed in 1950. In this paper, the information about principal, spraying techniques of fluidized bed processor and recent applications of FBP in pharmaceutical industries were reviewed. In face, it is more often than not the last step in the manufacturing process. The fluid bed system has a bed of solid discrete particle which are fluidized upward by passing a stream of air through a perforated sheet. The air is heated and the process hot air evaporate the fluid and dries the solid. There are three types of spraying techniques, the top spray commonly applicable for formation of granules to improve the flow characteristics of powder. The bottom spray is required for optimal application of coating material to the particle and achieves desire drying. The tangential spray used to ensure homogenous granulation. This insures good product at a lower cost than traditional drying methods. For instance, low moisture content in the polymer product is a prerequisite for subsequent extrusion processes. The main applications of fluidized bed processor, such as pelletization, particle coating, granulation powder and drying. This technology commonly employed for formed granules for tableting, capsule, excellent solubility, dust free process, fee flow properties, good dispensability due to porous structure.

Innovative liner concept using friction powder for increasing of broadband noise absorption. Applications for broadband noise absorption in fan duct

This paper presents research related influence of friction powders on enlarging the absorption band of acoustic liners used for reduction of tonal noise in fan duct of aero-engine. Kundt tube measurements done at COMOTI using fine powders (granules) made of various light-weight materials placed in the honeycomb cells of SDOF liners have shown a considerable broadening of the absorbed band of frequencies without a significant decreasing of absorption at the resonance frequency. Although the phenomenon is generally present for any type of powder, it was observed that for some powders the absorption is higher than for others. On the other hand, it was observed that the effect of the filling percentage of the cavity is important. Then, experiments done at the grazing flow facility of CNRS-Le Mans University have shown that the phenomenon is also present for high acoustic incident levels (up to 140dB) and M=0.13 while it still depends by the nature of powder material. The best results were obtained for the cork powder when the honeycomb is filled with powder at 66% of its height. For this material, the broadening of the transmission loss well was maximum. This phenomenon could be explained by the apparition of friction between powder granules which are taking place at very low scale consuming the noise power on a broader range of frequencies. It is supposed that the friction between the particles of powder have major influence because the best noise absorption was obtained for powders with a large distribution of particles’ dimensions while for particles with a small dimensional distribution (expanded polyester balls, for example) the transmission well broadening was smaller. The friction powders technology is simple and can be easily adapted to existing acoustic liner technologies with small manufacturing costs. This feature is conferred by the fact that powders can be easily poured in the honeycombs at the required height. The friction powder technology can be applied not only for the fan duct. In future, it could also be applied for reduction of jet noise reflected by pressure side of wing and for cabin noise reduction.

Effect of excipient properties and blend ratio on the compression properties of dry granulated particles prepared from microcrystalline cellulose and lactose

In this study, the effect of a systematically varied excipient ratio of a plastic and a brittle material, i.e., microcrystalline cellulose (MCC) and crystalline α-lactose monohydrate (LAC), on the compression properties of dry granulated particles was investigated. Five powders with different MCC:LAC ratios were prepared by dry mixing; subsequently, they were formed into slugs that were milled and sieved, giving granules of two size fractions. Two slugging pressures were used, giving granules of different porosity for each powder. Original powders and granules were compressed, and strain-pressure profiles determined. From these profiles, a series of compression parameters were derived using the Heckel, Kawakita, and Adams compression equations.The initial part of the compression profiles of all granulated powders were similar up to a jamming point, after which the compression profiles diverged depending on the granule composition and the slugging pressure. Parameters derived from the Adams and Kawakita equations reflected the differences in compression behavior, while the Heckel parameter did not. The macroscopic compression stiffening was assessed by the Adams friction parameter which seemed to be controlled by the inner friction of the granules, i.e., their plastic deformation due to inter-particulate flow. The total compressibility, assessed by the Kawakita parameter, was dependent on the initial bulk porosity of the granulations.It is concluded that the composition, microstructure, and packing density of the granules dictated their compression properties, while the granule size and work hardening of primary particles were insignificant.

Optimization of spray freeze drying parameters for spark plasma sintering of transparent MgAl2O4 spinel

Magnesium aluminate spinel (MgAl2O4) is considered as one of the most important spinels possessing desirable mechanical properties, with a wide range of applications at high temperatures. Powder granulation by spray freeze drying can lead to better powder flow and distribution in the mold, resulting in a specimen with high green density and strength. Accordingly, this study aimed at investigating the influential parameters on the granulation process of spinel powders via the spray freezing drying method. At first, spinel powders with various weight percents of 20, 25, 30, 35 and 50, and PVA binders with 0, 1, 2 and 8 wt% were investigated to prepare the optimal solution. Finally, the granules were sintered using the SPS method. The obtained bodies were tested by X-ray diffraction, SEM, FE-SEM, Viscosity and UV–Vis. The results showed that the optimal amount of the binder to obtain uniform granules in this process was 3%. Also, 35 wt% of solid loads represented the optimum amount for slurries, forming granules with the size range of 10–50 μm. By powder granulation, density experienced an increase of about 20%, leading to the growth of more than 15% in the in-line transmission for the IR range.

Determining rational process parameters for selective laser melting of powder titanium alloy VT6

The current pace of development seen by the aerospace industry requires manufacturing techniques that would enable to make parts in the shortest possible timeframe and at minimum cost. Additive manufacturing technology, which is applied in blanking operations, should be described as an innovative area that ensures reduced labour intensity and manufacturing costs. Additive manufacturing technology allows to obtain blanks that are close to the geometry of the final part, i.e. near net shape parts. Additive technology makes it possible to produce unique hollow parts with sophisticated cooling channels of any shape, as well as mesh filter elements with the cell size determined by the size of the powder granules. Thus, printing of parts using metal powders would be of special interest for the aerospace industry. Selective laser melting (SLM) as one of the additive manufacturing areas is of relevance for the aerospace industry as it enables to obtain parts with a more sophisticated geometry in comparison with conventional technology. One of the key stages in the SLM process design that defines the mechanical properties of the synthesized material includes identifying rational parameters of scanning. This paper describes the results of a study that attempted to determine rational scanning parameters for powder titanium alloy VT6. Rational parameters of scanning were established through statistical processing of experimental data. Thus, they include the laser power of 275 W, the scanning pitch of 0.12 mm, the scanning speed of 805 mm/sec, with the layer thickness of 50 μm. The paper describes the results of a uniaxial tensile test carried out with cylindrical specimens produced at 0o, 45o and 90o to the dosing unit and at 0o, 45o, 60o, 90o to the base platform.The research work described in this paper was carried out by the staff of the Shared Knowledge Centre on its equipment using CAM technology; Agreement No. RFMEFI59314X0003.

Towards a better understanding of thermally treated polycarbophil matrix tablets for controlled release

Polycarbophil (POL), a polyacrylic acid cross-linked with divinyl glycol, is widely used in semisolid and solid dosage forms. When undergoing a thermal treatment in the range 120–160 °C, POL shows interesting morphological modifications, related to changes in physical properties, such as swelling of the powder granules, or hardening and matrix formation if included in the composition of a tablet. Thermal analysis conducted on POL highlighted a thermal event (Z) that can be correlated both to the shrinking of the powder granules and to the matrix formation in compacted POL powder. Modulated differential scanning calorimetry (MDSC) allowed to distinguish, inside event Z, an irreversible process overlapping with a reversible glass transition, attributable to the volatilization of residual solvents identified, through a complex TGA-FTIR-GC–MS interface, as acetate esters used for the polymer production as very fine powder. A specific interaction between acetates and POL, capable of stabilizing the polymer chains in a given conformation, was highlighted. The molecular rearrangement of the POL chains, following the volatilization of the solvent-stabilizers, is therefore ascribable to a loss of energetic stability of this material, which justifies the shrinking phenomena in the granules of the powder and the matrix formation when POL is compacted.

Influence of powder state and rheology on sintering behaviour of SiC

The influence of conditioning state of a nano-SiC powder on its spark plasma sintering behaviour and microstructural properties is discussed. The powders were firstly deeply characterized by means of SEM, X-ray diffraction, specific surface area measurements and rheological behaviour determination. We found that even if the initial particles are the same, the conditioning state plays a crucial role on the development of the ceramic. Granulated SiC powder exhibits the highest ability of rearrangement and compaction leading to a better green density. This specificity allows the development of the densest ceramic with the lowest grain size. Moreover, this ceramic showed no evidence of phase transition during sintering, with a pure cubic SiC phase. We conclude that the powder state and the storage conditions of the ceramic powder has an impact on the overall powder process and finally influences not only the final density and grain size but also the phase composition.

Выбор метода изготовления пористых порошковых изделий фильтрующего назначения

The article considers three methods of increasing the distribution uniformity of properties over the filtration area of powder filter materials at different stages of their manufacturing. It is shown that granulation of metal powders with a pore former increases the uniformity of permeability distribution over the filtration area by a factor of 2.3–3.5. Dry radial isostatic pressing ensures high distribution uniformity of properties, while the coefficient of variation of local permeability does not exceed 0.17. Radial compression allows increasing the uniformity of permeability distribution over the filtration area by 15 ... 22 % compared to that for the original powder filter materials. The selection of the method used in practice is determined by the shape, size and properties of the manufactured products and initial powders. The considered methods can be used in petrochemical engineering for the manufacture of porous powder products for filtering purposes, used to trap catalyst particles, filters for fine and coarse fuel and oil purification.

Freeze granulation and spray drying of mixed granules of Al2O3

This paper proposes a comparative study of two techniques of granulation of a submicronic alumina powder with high binder content slurries, by spray drying and freeze granulation for the preparation of mixed granules. First, the viscosity and flow index of the suspensions are given as a function of dispersant, solid and binder contents versus alumina content, and the data are analysed in order to give a predictive model in a wide range. Suspensions with varying viscosities (7–208 mPa.s), densities (1.31–1.76) and surface tensions (23–40 mN/m) were then granulated. The first observations reveal the importance of the content and the molar mass of the binder: when they are too high, the freeze granulation fails and filaments are produced instead of granules due to extensive stretching of the molecular chains of the binder during spraying. Then through a theoretical analysis of the phenomena leading to granulation, an original dimensionless number is proposed to describe the evolution of the granule size as a function of suspension formulation. This number is related to the Reynolds and Weber number and is able to predict the granule size over a wide range (20–500 μm for freeze granulation, and 5–30 μm for spray drying). Spray drying leads to smaller granules with various shapes, from full shape to hollow or donut-like, whereas freeze granulation leads to bigger but spherical granules with a microporosity, and a size easier to predict as no drying shrinkage is observed.

Systematic study of paracetamol powder mixtures and granules tabletability: Key role of rheological properties and dynamic image analysis

The aim of this systematic study was to analyze the granulometric and rheological behavior of tableting mixtures in relation to tabletability by single tablet and lab-scale batch compression with an eccentric tablet machine. Three mixtures containing 33, 50, and 66% of the cohesive drug paracetamol were prepared. The high compressibility of the powder mixtures caused problems with overcompaction or lamination in the single tablet compression method; due to jamming of the material during the filling of the die, the lab-scale batch compression was impossible. Using high shear granulation, the flow properties and tabletability were adjusted. A linear relationship between the span of granules and the specific energy measured by FT4 powder rheometer was detected. In parallel, a linear relationship between conditioned bulk density and the tensile strength of the tablets at lab-scale batch tableting was noted. The combination of dynamic image analysis and powder rheometry was useful for predicting the tabletability of pharmaceutical mixtures during the single tablet (design) compression and the lab-scale batch compression.

Low temperature synthesis of Ga-doped Li7 La3 Zr2 O12 garnet-type solid electrolyte by mechanical method

Synthesis of Li6.25 Ga0.25 La3 Zr2 O12 (LLZO-Ga) solid electrolyte powder granule for all solid-state battery was investigated by applying mechanical processing of the raw powder materials adding LiF-BaF2 as a flux. The LLZO-Ga of highly crystalline was synthesized by the mechanical method using an attrition-type mill without any extra-heat assistance. When 10 mass% of LiF-BaF2 was added to the raw powder materials and 28 min processed, LLZO-Ga powder was favorably synthesized and granulated at the chamber temperature of 284 °C. The ionic conductivity of the sintered body of the LLZO-Ga granules was evaluated by impedance measurement. It revealed the high ionic conductivity of σtotal 1.0 × 10−3 S/cm. It suggests that the formation of LLZO-Ga/BaZrO3 grain boundary contributes to higher ionic conductivity adding to the high crystalline phase of LLZO-Ga.

Investigating the Effect of α-Fe<sub>2</sub>O<sub>3</sub> Oxides on the BaFe<sub>2</sub>O<sub>4</sub> Pyrosynthesis Temperature - The Digital Processing of TG and DTA Curves

In the research activities on the barium monoferrite pyrosynthesis, an important place is occupied by TG and DTA analysis. The effects of different hematite (α-Fe2O3) granulations on the BaFe2O4 pyrosynthesis temperature were followed. Four types of commercial hematite powders were used, the difference between them being the fineness of the powder granules and the purity. Only one type of commercial barium carbonate (BaCO3) powder was also used as a barium additive in the BaFe2O4 pyrosynthesis. Each of the 4 types of α-Fe2O3 with BaCO3 were subjected to the homogenization process in a planetary mill for a more intimate mixing of the powders in order to obtain error-free results regarding the pyrosynthesis reaction. To determine BaFe2O4 pyrosynthesis temperature, a derivatograph device was used. All the data obtained with this thermal device were digitally processed in order to extract the two TG and DTA curves. The protective atmosphere in the furnace was nitrogen. BaFe2O4 pyrosynthesis temperatures recorded different values for the four mixtures, depending on the particle size of the α-Fe2O3 powders, protective atmosphere from furnace and the mixing conditions. The effects of Fe2O3 oxides on the BaFe2O4 pyrosynthesis temperature is observed when are used very fine hematite powders in mixtures, obtaining a reduction of pyrosynthesis temperature up to 16% compared to the mixture where the size of the hematite is coarser.

폐콘크리트 및 폐모르타르로부터 분리된 미분말의 물리적·화학적 특성 평가

이 연구에서는 방사화 폐콘크리트의 부피감용을 위한 건식 재활용 기술 개발의 기초 연구로서 폐콘크리트 및 폐모르타르에서 분리된 미분말의 물리･화학적 특성을 평가하였다. 미분말의 재활용을 위한 건식 처리 방식은 분쇄, 소성 및 재수화의 방식이 이용되었다. GGWCPs에서 측정된 특성 및 활성도 지수는 보통포틀랜드시멘트, 플라이 애시 및 고로슬래그 등의 일반적 특성 및 규격에서 요구하는 최소조건과 비교하였다. 재수화 미분말의 비표면적은 약 4,000 ㎠/g으로서 ASTM C150에서 제시하고 있는 OPC의 요구품질(2,800 ㎠/g 이상)을 만족하였다. 폐콘크리트 미분말의 화학적 조성은 OPC와 같이 CaO 및 SiO₂에 의해 지배되었으며, 열분해에 의한 시멘트 수화물(portlandite 및 calcite 등)의 질량 감소는 소성 및 재수화의 처리 공정을 실시한 시료에서 더 적게 나타났다. 소성처리를 실시한 미분말의 재령 28일 활성도 지수는 80 % 이상 수준으로서 이는 플라이 애시 2종, 3종, 4종 및 고로슬래그 미분말 3종의 품질기준(80 % 이상)을 만족하였다.

Determination of limiting factors in a novel superconcentration-granulation based dairy powder manufacturing process

An innovative approach based on superconcentration and granulation was investigated to manufacture dairy ingredients at lab-scale. A wet mass characterization technique, which measured agitator current consumption, was developed to study cohesiveness of super-concentrated products at various dry matter (DM) contents. For all ingredients, a composition-dependent cohesive phase was observed as DM increased, which was typified by a sharp rise and subsequent fall in power consumption. The effect of powder back-mixing on granulation was studied using three superconcentrate:powder (w/w) ratios (1:0.8, 1:1 and 1:1.2, respectively). Minimum powder addition rate for successful granulation was related to DM content at the end of the cohesive phase. Granulated powders had larger particle size, higher densities, lower porosities and enhanced flow properties compared to commercial spray-dried powders. The lab-scale model provided useful information on physical properties and limits during superconcentration and granulation, which increases the scientific knowledge relating to this novel powder production approach. Industrial relevanceSpray drying is the most widely utilized powder manufacturing technology in the dairy industry, especially for producing ingredients and nutritional products. It is, however, extremely energy intense and therefore spray drying of high-volume, low-value dairy streams such as permeate represents a poor use of resources for industry. An alternative spray dryer-free process has been developed for such streams, with significant savings. This process is based on superconcentration of streams to DM content in excess of what is typically seen in a spray-drying process (up to 80% w/w DM) followed by granulation achieved by back-mixing of finished product and, finally, drying of granules. However, little information is available on how various dairy ingredients behave in this system. Therefore, a novel lab-scale production model was produced to determine limits of superconcentration and granulation behavior of various ingredients. This work provides vital information and represents the first step in a larger program which will culminate in demonstration of the industrial applicability of the new approach for drying of various dairy streams.