ultrafine wet grinding

china lhe wet ultrafine grinding mill factory and manufacturers | zhengyuan

china lhe wet ultrafine grinding mill factory and manufacturers | zhengyuan

The LHE Wet Ultrafine Grinding Mill is a large size grinding machine independent r&d by our company. Fully new grinding structure, unique component design, succinct process, it has qualitative improvement compare with other vertical wet grinding machine. With advantages of high grinding efficiency, fineness particle size and lower grinding media consumption ,it is the best solution for -2m powder ultrafine grinding.

The LHE Wet Ultrafine Grinding Mill is a large size grinding machine independent r&d by our company. Fully new grinding structure, unique component design, succinct process, it has qualitative improvement compare with other vertical wet grinding machine. With advantages of high grinding efficiency, fineness particle size and lower grinding media consumption ,it is the best solution for -2m powder ultrafine grinding.

Firstly, the wet material will be pumped into the grinding machine which is prepared with a certain amount of grinding mediums. Then, the driving part will drive the mixing parts to rotate in a high speed. Due to this, the wet materials and grinding mediums will also rotate at a high speed, thus the raw materials will be ground into ultrafine materials under the impact force, shearing force and collision force between grinding mediums. Finally, the ultrafine materials will be filtered by the vibrating screen, and then will be discharged from the discharging hole and collected by the collection system.

LHE wet ultrafine grinding machine is the newly-developed grinding equipment of our company. Designed with totally-new machine structure, optimized machinery size, uniquely- designed machinery parts, and simplified production process, this wet ultrafine grinding machine has higher performance. Its advantages include:

1. High efficiency For producing the same amount of material, this wet ultrafine grinding machine consumes 30% less energy in comparison with conventional grinding equipment. 2. High fineness of finished products The size of grind-need material ranges from 200mesh to 325mesh, and the finished material fineness is 2m. 3. The parts inside the grinding machine are made of high hardness, wearing-resistant materials. Hence, the grinding machine features long service life. 4. The starting torque is low, and as a result the grinding machine produces a small impact on power grid. 5. The finished material has a low temperature, low viscosity, and good fluidity. 6. The wet ultrafine grinding machine can be used independently or used in combination with each other. 7. Fully automatic controlled, easy to operate, and the production capacity is stable. 8. Low loss of grinding medium, and as a result, there is no pollution on materials.

Our wet ultrafine grinding machine can be used for grinding the following materials: 1. Non-metallic materials: calcium carbonate, kaolinite, soft kaolin, barite, bentonite, brucite, tourmaline, mica, rare earth, etc. 2. Energy source materials: Water coal slurry, petroleum coke slurry, etc. 3. Ceramic materials: zirconium silicate, zircon powder, -alumina, etc. 4. Metal: superfine gold and silver ore, molybdenum ore, copper ore, manganese ore, aluminum-zinc ore, etc. 5. Chemical materials: aluminum hydroxide, magnesium hydroxide, manganese dioxide, flame retardants, catalysts, iron oxide red, sulfur, metal oxides, and more.

wet ultrafine grinding mill_weifang zhengyuan powder engineering equipment co., ltd

wet ultrafine grinding mill_weifang zhengyuan powder engineering equipment co., ltd

Take the promotion of powder processing level as its own responsibility.Put independent technology research & development & product innovation and improvement in the first place in enterprise development. Update technologies,to serve the powder industry.

The slurry is fed into the mill by the feed pump. The mill is equipped with a fixed amount of grinding media. The transmission mechanism drives the agitator to rotate at high speed. The slurry is grinded, squeezed, impacted, and sheared by the grinding media. The finished pulp is filtered through the screen and then flows out of the discharge port into the collection system.

The LHE wet ultrafine grinding mill is a large-scale wet crushing equipment newly developed by our company: new mill structure, optimized mill size, unique component design, simple process, equipment performance is better than other vertical wet mills Qualitative improvement. Main performance advantages: 1. High grinding efficiency: the energy consumption per ton of product is reduced by 30% compared with other wet grinding. 2. The fineness of the finished product is high: feeding 200 mesh ~ 325 mesh, crushing fineness-2m particle size 95%. 3. The internal parts of the mill are made of high-hardness wear-resistant materials, and the equipment has a long service life. 4. The starting torque is low, and the impact on the grid electrical appliances is small. 5. The temperature of the finished slurry is low, the viscosity is small, and the fluidity is good. 6. A single unit can work independently and continuously, or multiple units can be used in series. 7. The production line adopts automatic control, convenient operation and stable production. 8. Low abrasive wear and no pollution to the product.

Gold and silver ore, molybdenum ore, copper ore, manganese ore, aluminum and zinc ore, ultra-fine beneficiation and regrind; Chemical industry: aluminum hydroxide, magnesium hydroxide, manganese dioxide, flame retardant, catalyst, iron oxide red, sulfur, metal oxide, etc.

preparation of ultrafine fly ash by wet grinding and its utilization for immobilizing chloride ions in cement paste - sciencedirect

preparation of ultrafine fly ash by wet grinding and its utilization for immobilizing chloride ions in cement paste - sciencedirect

The wet grinding process greatly promoted the reactivity of FA.UFA showed higher efficacy in improving chloride immobilization than RFA.UFA increased chloroaluminate salts to strengthen chemical binding.UFA could refine pore structure to hinder chloride migration.

In this study, to promote the chloride binding capacity of coal fired fly ash (RFA) in cementitious materials, wet grinding was employed and ultrafine fly ash (UFA) with D50=2.1m was prepared; SEM, XRD, TG, FTIR, and XPS were used to evaluate the chemical and physical change in the process of wet grinding. Then, two kinds of binders composed of cement and FA were designed, and the chloride immobilization was comparatively studied in terms of chemical binding, physical binding, and migration resistance. The hydration behavior and hydrates were investigated in terms of TGA, XRD, NMR, and MIP. Results revealed that UFA exhibited higher pozzolanic reactivity due to the increase of specific surface area, destruction of original molecular structure, and exposure of active reaction sites. And chloride immobilization in cement-UFA system was much greater than that in cement-RFA system at ages of 7 d and 28 d. The mechanism behind was discussed in three aspects: (a) chemical binding was promoted because of the more produced chloroaluminates facilitated by the release of aluminum from UFA; (b) physical adsorption was strengthened at 7 d but weakened at 28 d, resulting from the opposite influence on the amount of C-S-H gel at different ages; (c) migration resistance was improved by the reduction of pore volume and the increase in the complexity of pore structure. This investigation provided one new method for processing FA to promote the chloride immobilization of cement-FA system.

ultrafine grinding - an overview | sciencedirect topics

ultrafine grinding - an overview | sciencedirect topics

PTFE ultrafine powder can be prepared by irradiation at room temperature, followed by ultrafine grinding. Fresh PTFE material, scrap or recycled PTFE waste, etc., can be used to fabricate ultrafine powder. The use of recycled PTFE or waste to produce ultrafine powder can reduce the cost and achieve the recycling of resources. PTFE ultrafine powder is widely used as a functional additive in the fields of engineering plastics, anticorrosion coatings, nonstick coatings, coil coatings, powder coatings, and inks. Shamrock Technologies (the United States), Solvay Company (Italy), Lubrizol Corporation (Germany), Kitamura Company Ltd. (Japan) and many other companies produce PTFE ultrafine powder. In recent years, domestic Chinese enterprises have also made great progress in the technology of manufacturing PTFE ultrafine powder. Fig. 5.17A (average particle size: 2.43m) and Fig. 5.17C (average particle size: 4.26m) shows the appearance and particle size distribution of two kinds of PTFE ultrafine powder, prepared by Jiashan Senga Tech Co., Ltd., China.

Figure 5.17. Photographs and particle sizes of two kinds of PTFE ultrafine powder: A, the appearance of PTFE ultrafine powder with the average particle size of 2.43 m; B, the particle size distribution of sample A; C, the appearance of PTFE ultrafine powder with the average particle size of 4.26 m; D, the particle size distribution of sample C.

The particle size of PTFE powder is usually tens to hundreds of microns, which is suitable for producing PTFE sheet and pipe. PTFE ultrafine powder can be made by polymerization, radiation degradation, and thermal cracking. The irradiated PTFE becomes very brittle, and can be further fabricated into ultrafine powder by grinding or air-jetting. The particle size is closely related to the absorbed dose. The higher the absorbed dose, the lower the relative molecular weight of PTFE, and the smaller the particle size of ultrafine powder. At present, PTFE ultrafine powder is mainly prepared by radiation degradation at home and abroad, since high energy beam can effectively break the molecular chains of PTFE at room temperature. For recycled PTFE, a very high absorbed dose is required for the fabrication of PTFE ultrafine powder. Hence, it is normally irradiated by EB accelerators. PTFE ultrafine powder is mainly used as an additive in lubricating oil and grease, ink, paint, engineering plastics, leather, rubber, etc., in order to improve antifriction and scratch-resistance.

The CNF was extracted from carrot residue supplied by Brmhults AB, Sweden by a ultrafine grinding method developed at LTU24,25 (Fig. 2). The residue was first washed and then pretreated using NaOH followed by bleaching using sodium chlorite and finally washed to a neutral pH.25 The grinding was performed with a supermass collider (Masuko Sansuko, Japan, MKCA6-2), until a gel was formed with a CNF content of 1.4% (98.6% H2O). The wet fibers were then centrifuged to a concentration of 8 wt% (Beckman Coulter J25i). Higher concentrations were limited due to the increasing viscosity of the gel.

The sandwich composite was manufactured with a bio-PU foam core, Kraft paper skin, and epoxy resin as matrix. The Kraft paper was an Absorbex Eco Kraft paper (Kotkamills Oy, Finland, TI352_040_0) made from sawdust and recycled fibers with a weight of 30 g/m2. The resin was a mixture of low viscosity epoxy with a slow hardener (Plastic World, Canada, West System 105/206). It had a mixed density of 1180 kg/m3 and viscosity of 725 cps at 22C.26

Figure37 is an example of SPSed component in an actual commercial use in the optic industry which is aspheric glass lens molds made of a binder-less pure-tungsten carbide (WC single phase, Hv2600) material without additives and not containing the W2C phase. They were homogeneously consolidated in nanostructured fine grain size. By using ultra-fine grinding machine, the super finishing of mirror surface roughness of Ra510nm can be obtained to fit with digital camera lens application. The aspheric glass lens mold consists of three pieces: upper punch, lower punch, and sleeve die part. The advantages of SPSed pure WC material are solid-phase sintering, attaining finer grain, and higher oxidation resistance compared to conventionally produced other binder-less WC materials. Under 973K in atmospheric furnace with 10hours running test, it resulted in a 3060% better oxidization in volume (g/cm2).

Commercial microfine cements were developed in Japan for grouting, after organic grouts had been banned in 1974. (Grouts are materials including neat cement injected into a soil or rock formation to change the physical characteristics of the formation.184) Microfine cements are produced in classifiers or by ultrafine grinding in a cement mill to a high surface area, commonly 600 m2/kg or above. They work on the principle that the more finely ground the cement, the greater is the penetrability. A penetrability comparable to that of chemical grouts can be achieved. Microfine cements can be of Portland cement or Portland cement-extender mixes, where the commonest extender used is ground granulated blastfurnace slag. Injection of cement grout under pressure is sometimes used for sealing contraction joints in mass concrete structures such as domes, for repairing cracks in concrete and for tightening water-retaining structures. In use for grouting, the microfine cement is commonly batch-mixed with water and a dispersant or in a two-component mix with sodium silicate in the second tank. With a given commercial microfine cement, the batch system has produced setting times of ca. 45 h and the two-component mix very rapid setting times of 13 min.184 Microfine cements are increasingly being used in oilwell cementing squeeze repair jobs.19

Abrasion induced by friction, as one of the main causes of materials failure, has caused huge pecuniary loss each year all over the world, and thus far various nanomaterials have been used as lubricating additives to reduce friction and wear. Palygorskite as a 1D nanomaterial has also received much attention in lubrication additives. It was found that the basic oil containing 0.5wt% of palygorskite nanorods can remarkably decrease the friction coefficient and wear rate of carbon steel friction couples due to the formation of a smooth and compact tribo-film composed of multiple oxides on the worn surface [479]. The ultrafine grinding treatment of palygorskite as an additive of mineral oil can further improve friction-reduction and antiwear properties because a tribofilm mainly composed of FeO, Fe2O3, FeOOH, and SiO can be formed on the worn surface lubricated with oil more easily [480]. The adding of fine palygorskite powder into engine oil (Great wall CD 15W/40) may decrease its friction coefficient [481]. In addition, palygorskite also can be used as an additive of lubrication grease. The lubricating grease, using surface-modified palygorskite clay as thickener and synthetic oil (PAO 40) as the base oil was prepared and compared with that of traditional bentone grease, and it was found that the palygorskite clay grease containing MoS2 had a better friction-reducing ability than the traditional bentone grease containing MoS2 [482]. The addition of Cu nanoparticles [483], spherical Nano-Ni (0.1% addition) [484], and ionic liquids [485] into the palygorskite base grease may improve its friction-reduction ability and antiwear property.

Ball milling (solid-state synthesis) is one of the most important processes used in industry to synthesize nanomaterials, and is also called mechanical alloying or attrition. This method is based on a top-down approach, like self-assembly of molecules and reducing the size of the larger particles. The principle involved in the milling process is the generation of frictional force due to the collision between the reactants surface, which leads to increased temperature, pressure, and internal energy [2227].

Ultrafine grinding or nanosizing terms were frequently used for the process, when the size of the particle lies in the range of nanometers compared to the other synthesis method. Mechanical attrition methods lead to higher production rates (tons of nanomaterials can be produced in an hour) and widely used in industrial production like metal, clay, and coal powders [2228]. The chemical reaction takes place in a very short time interval in the ball milling process.

The modification mechanism takes place by breaking the molecular bonds or changing the reagents reactivity. Using the ball milling process for grinding, the structure of SWCNTs shows a decrease in length and increase in surface area, which is a condition required for varied catalytic supports [26,29]. Some of the recent researches have shown the aniline absorption behavior of milled CNT and un-milled CNT in fluid solution [30]. The functionalization of SWCNTs with aryl and alkyl groups mixed through a high-speed vibration mill shows modified surfaces of carbon because of the continuous alkyl chains, well soluble in regular organic solvents [31,32]. In chemical and mechanical methods, the existence of ammonium bicarbonate was introduced, with amine and amide groups for the in situ functionalization of nanotubes [32]. Also, the semiconducting behavior conversion takes place between p-type to n-type. Ball milling at ambient conditions reduces the MWCNTs and the morphology of broken end cleavage, proposing a different mechanism. At the solid phase, SWCNTs were modified using a mechanical-chemical reaction at room temperature in the presence of potassium hydroxide [33]. It was found that within 10min the metal nanoparticles on the surface of nanotubes got deposited using a simple mechanical-chemical process

One prerequisite for the combination of system-on-chip (More Moore) and system-in-package (More than Moore) to achieve higher-value systems is integration, seeFigure18.1. Portable devices like smartphones, tablets or smart watches, today's technology drivers, are getting smaller and smaller, so that integration on printed circuit boards is no longer sufficient. Stacking chips and connecting them by means of wire bonding or, even more space-saving, by means of TSVs leads to high-density 3D integration.

Meanwhile, today's very high wafer manufacturing quality allows 3D wafer-on-wafer stacking by means of vertical interconnects with high yield. The technologies necessary for this bonding approach are wafer thinning and formation of TSVs. The wafer thinning process consists of the following steps: temporary bonding on handle wafers or grinding tape, backside grinding down to 5075m thickness, smoothing the grinded surface by ultra-fine grinding, etching or CMP and the subsequent wafer transfer onto the main carrier wafer. The formation of vertical interconnects as TSVs consists of deep silicon etching, sidewall isolation, filling with conducting materials like high-doped poly-Si or metals like copper or tungsten and removal of the overburden material by means of CMP. In both cases, planarization processes by means of CMP are key enabling technologies.

Advanced wafer grinding allows the thinning of silicon wafers down to 50m or even less. Depending on the finish grinding wheel used, grinding marks and a disturbance of the crystal structure, the so-called subsurface damage, have to be removed. Since the depth of the disturbance can reach several micrometres, a sufficient compromise is to remove about 5m by means of etching or CMP. If the wafers subsequently have to be bonded, the surface has to be polished. Very good results have been obtained in the author's lab by using a two-step process derived from the prime wafer manufacturing process. The first step is a bulk removal step using a fumed-silica-based slurry like Cabot's SS25 on an IC-type polishing pad in order to achieve the desired thickness followed by a 90s haze-free step with a typical haze-free slurry like Fujimi's Glanzox 3900 on an SPM-type pad to get a nearly atomically flat surface. A particle-insensitive hydrophilic surface is obtained after post-CMP brush cleaning by means of an SC1 treatment.

Using TSVs allows the formation of vertical interconnects between the bonded wafers. When copper is used as the filling metal of the vertical via holes, thermal compression bonding can be used for electrically connecting the bonded wafers. However, because of the high roughness of the as-deposited surface of several 10nm, the standard parameters for thermal compression bonding of T=600700C and pressures of several MPa are not compatible with back-end-of-line device fabrication parameters. Researchers at Fraunhofer ENAS (Schubert etal., 2011) have reported that polishing by means of Cu CMP leads to a 2040 improvement of surface smoothness, which allows a thermal compression bonding of test wafers at only 400C with a pressure of 0.6MPa (90psi), applied for 2h. The CMP step was performed with a Cabot EPL-series Cu slurry on a soft pad at 1.5psi for about 90s. Post-CMP corrosion was prevented by using a weak organic acid during brushing and a subsequent inert gas treatment at moderate temperatures.

In nature, cellulose does not appear as an isolated individual molecule, but it is built-up of self-assembled individual cellulose chain-forming fibers. Cellulose has a hierarchical structure of the nanoscale building up to the microscale by nature. Composite materials possess two or more constituent materials with considerably different physical or chemical properties; these constituents on combination produce a material having different characteristics from the individual components. Cellulose macro- and nanofibers can be employed as reinforcement in composite materials to develop extraordinary biodegradation, mechanical, and thermal properties of composites.

Micro fibrillated cellulose (MFC) is generally prepared from wood by the high-pressure homogenization of pulps. Numerous steps as pretreatment have been projected to assist this process, for instance, acid hydrolysis, enzymatic pretreatment, mechanical cutting, and generation of charge groups through 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation. MFC is the tiniest structural unit of plant fiber; hence, it comprises a package of strained cellulose chain molecules with entangled, long, and flexible CNF of almost 1100nm size. Further, these cellulose chain molecules contain of discontinuous amorphous and crystalline domains [92].

CNF have a diameter of about 3nm and lengths in the micron scale showing both crystalline and amorphous sections. They can be produced from cellulose microfibers [93]. CNF are developed by mechanical fibrillation, which includes homogenization, microfluidization, or ultrafine grinding, of cellulose biomass, according to the cellulose source and pretreatments [33]. Some time, pretreatments, like enzymatic pretreatment, chemical pretreatment, or mechanical pretreatment, are performed on CNF in order to reduce energy input, improve CNF quality, or achieve other purposes [71].

CNC, generally extracted by acid hydrolysis of cellulose, are needle-shaped entities. Acid hydrolysis destroyed the amorphous regions in the crystalline and those fixed between microfibrils, remaining the crystalline sections together [31]. Consequently, acid hydrolysis of native cellulose encourages a sharp decrease in its degree of polymerization [94]. The diameter and length of the CNC depend upon the cellulosic source material and the conditions of preparation. Nevertheless, the diameter lies in nanometers, while the length varies from tenths of nanometers up to several micrometers. Other than sulfuric acid, acids like hydrochloric, phosphoric, and hydrobromic acids have also been used acid for the isolation of CNC [71]. Nanocellulose has attracted a wonderful attention in the materials community because of their exclusive physical, mechanical, and chemical properties. Nanocellulose has been used as a reinforcing phase in polymers and is an emerging area in further research [42]. It was found that the tensile modulus and strength nanocelluloses are around 145165GPa and 10,000MPa, respectively [24]. CNC and CNF can also be applied in different fields like food additives, paper and packaging, lightweight composites for aerospace and automotive, personal care products, biomedical products, rheology modifiers, coating components, and optical devices [29].

Nanocellulose can be modified by direct chemical changes and/or covalent affection of molecules. Outstanding adsorption behavior may be acquired with various kinds of altered nanocelluloses because of their high specific surface areas and several reactive groups. Loading of native cellulose noticeably enhances metal elimination capability compared with rice straw and cellulose fibers. Nanocellulose fibers were synthesized by the physical and chemical action of rice straw and were characterized and discovered for the elimination of some toxic metals from contaminated water [95]. Nanocellulose fibers showed long rodlike extended nanofibrillated structure, having a normal grain size of 6nm. Nanocellulose fibers synthesized in batch experiments revealed an elimination capability, efficiency of 9.7mg/g Cd(II), 9.4mg/g Pb(II), and 8.6mg/g Ni(II) ions. The restoration studies confirmed that nanocellulose fibers could be consecutively used for up to three cycles of regeneration. More surface area of the altered nanocellulose might prove a fascinating alternative to old adsorbents like activated carbon, ion-exchange resins, or zeolite. This high potential surface area of nanocellulose in water treatment opened the door to produce adsorbents based on altered nanocellulose for elimination of heavy metal ions and organic contaminants. The surface alteration of the nanocellulose was followed by adding specific groups like carboxyl [96], amine [8], ammonium [97], and xanthate [98] on the surface of cellulose. Succinic anhydride was investigated for the modification of cellulose to removal of heavy metal ions [96]. Nanocellulose-ethylenediaminetetraacetic acid (EDTA) pairs were developed by the esterification of nonmercerized and mercerized cellulose with the help of ethylenediaminetetraacetic dianhydride (EDTAD). The altered cellulose materials exhibited highest adsorption capacities for Cu(II), Cd(II), and Pb(II) ions ranging from 38.8 to 92.6, 87.7 to 149.0, and 192.0 to 333.0mg/g, respectively. Also, it was found that altered mercerized materials exhibited higher adsorption capabilities than altered nonmercerized materials [99]. NCC reveals outstanding features for metal elimination due to the more surface-to-volume ratio and the capability to modify the surface characteristics by molecular modification. The elimination capacities for succinated and aminated NCC were found 95.0% for Cr(III) and 98.0% for Cr(VI) compared with unmodified NCC 64.0% for Cr(III) and 6.0% for Cr(IV) [8].

Reaction of cellulose with carbon disulfide (CS2) in the presence of sodium hydroxide (NaOH) prepared sodium cellulose xanthate. This esterification reaction was employed to develop acid-hydrolyzed nanobanana cellulose. It was observed that the highest biosorption capability of xanthate nanobanana cellulose for Cd(II) was 154.3mg/g [100]. Bacterial cellulose (BC) showed a relatively low adsorption capacity [3]. Therefore, the surface modification of BC is necessary in order to enhance its adsorption capacity. Different BCs [101] were used as adsorbents for the elimination of Pb(II), Cu(II), Cr(VI), and Cd(II).

Nanocomposites actually consist multiphase materials in which at least one constituent phase possessed one dimension in the nanometer range (1100nm). These materials are acknowledged because of their barrier, mechanical and superior thermal properties, and their good recyclability against conventional composite materials [102]. The nanocellulose-based bionanocomposite materials used for water treatment are presented in Table 16.2.

Nanoscale cellulose fiber materials, such as nanofibrilled, microfibrillated, and BC, are excellent applicants for bionanocomposite development due to their unbeatable properties like high strength, abundance and low weight, stiffness, and biodegradabity. Nanocomposite material characteristics depend on the addition of their distinct constituents and on structural and interfacial properties emerging from the combination of different materials. Therefore, the use of polymers such as cellulose, dextran, starch, alginate, carrageenan, and chitosan attracted huge attention because of their renewable nature and biodegradability, also a numerous combination is expected to depend on the predicted functionality [103].

Cellulose nanofibril was covered with magnetic nanoparticles that are uniformly distributed on the nanofibril. In this way, these materials showed both biological and mechanical properties of nanocellulose, which thereby increases due to magnetic nanoparticle characteristics [104]. The spherical Fe3O4/BC nanocomposites had high adsorption capacities toward Pb(II), Mn(II), and Cr(III) and found recyclable after the elimination of heavy metal ions [45]. Spherical Fe3O4/BC nanocomposites can be easily developed without sophisticated steps as compared with conventional preparation method for cellulose spheres, and this spherical composite material has high adsorption and elution capacities. Composite hydrogels from cellulose and other biopolymers have been synthesized by blending, complex formation, and interpenetrating networks technology [105]. Biodegradable collagen/cellulose hydrogel beads (CCHBs) were studied [46]. The maximum adsorption capability of CCHB3 (collagen/cellulose mass ratio of 3:1) was found 63.6mg/g. PVA was also studied for synthesis of hydrogel by cross-linking it with several methods [50]. Butylmethylimidazolium chloride (Bmim+Cl) IL was employed as the solitary solvent for the dissolution and formation of the composites. Chitin/cellulose composite membranes demonstrated the effective elimination of heavy metal ions from an aqueous solution due to their microporous structure, large surface area and affinity for metal ions [47]. The elimination efficiency of the heavy metal ions on chitin/cellulose blend membranes enhanced with the chitin content. Nanocellulose acetate has been applied as composite material together with zirconium (IV) phosphate and zeolite for the elimination of heavy metals from aqueous solutions [44].

Stirred media mills are used by the mining industry for ultrafine grinding to enhance liberation, and to decrease particle sizes of industrial minerals to tailor functional properties. This review describes stirred media mill technologies and operating principles, and summarises stress intensity theory which can be used for selecting efficient operating conditions. For fine and ultrafine grinding, the Bond work index is an inappropriate measure of grindability, so alternatives are discussed. Using literature data, the variation in the appropriate energy-size models between examples is assessed, and rationalised with stress intensity theory. A Rittinger operating index was found to be the best choice for assessing operation efficiency. Finally, a modification of stress intensity theory that tunes operating conditions based upon material properties, and the fmat mastercurve theory are discussed, with the conclusions that, although promising, laboratory-scale milling tests remain the most practical method of assessing material grindability and predicting industrial energy requirements.

Calcination of certain aluminosilicate raw materials is necessary in order to render them sufficiently reactive. For example, for dehydroxylation of the commonly used kaolin into metakaolin (at approximately 600C), the main phenomena are the transformation of octahedral Al into tetrahedral Al, structure amorphization, and retaining a 1:1 layer type [151]. With one-part geopolymer mixes, an alkali source, such as NaOH, is commonly added to the calcination phase and the process is referred to as alkali fusion. The addition of sodium to the aluminosilicate increases the number of non-bridging oxygens [85]. It is notable that in some cases, calcination without the alkali addition was not sufficient to alter the structure into reactive form (e.g., with albite up to 1000C) [85]. In addition to calcination, mechanochemical treatment (e.g., high intensity ultra-fine grinding) can also be utilized in activation [75].

Bentonite [116,152], kaolin [115,153], halloysite [154], albite [85], and red mud [74,96] are examples of aluminosilicates used in one-part geopolymers that have been calcined (at 5501100C) with the alkali fusion method (see Table 1). The optimum calcination temperature is dependent on the material used: for instance, in the case of bentonite activated by dolomite or Na2CO3, calcination at 1100C was better than calcination at 1200C [152]. Interestingly, quartz, which is commonly present as an impurity in bentonite, became a reactive glassy phase at 1000C with 20% NaOH present [152]. However, increasing the calcination temperature can also increase crystallization of aluminosilicate phases, which has a negative effect on geopolymerization due to the unreactivity of such phases. Peng et al. [116] concluded that Na2CO3 is more effective than NaOH in high-temperature alkali fusion of bentonite. Increasing the calcination temperature of kaolin with NaOH or Na2CO3 up to 950C had a positive impact on the compressive strength [116].

However, calcination of raw materials introduces an additional step to the manufacturing of one-part geopolymers and can increase the carbon footprint. In some cases, the activators that are added during calcination, such as dolomite or Na2CO3, also introduce CO2 emissions. Numerous studies have demonstrated (see Table 1) that calcination can be avoided with the appropriate selection of aluminosilicate raw materials (such as fly ash and blast furnace slag), although, fly ash and blast furnace slag themselves have been formed in high-temperature processes.

key role of mild sulfonation of pine sawdust in the production of lignin containing microfibrillated cellulose by ultrafine wet grinding - sciencedirect

key role of mild sulfonation of pine sawdust in the production of lignin containing microfibrillated cellulose by ultrafine wet grinding - sciencedirect

Mild sulfonation of sawdust prior to ultrafine wet grinding was studied.Sulfonation enhanced grinding efficiency and the bonding capability of microfibrils.Fibrillation is based on lignin softening and the fatigue of cell wall ultrastructure.Sulfonation is a green and low-cost method to improve wood fibrillation.

Cheaper methods and raw materials are currently being sought for the production of microfibrillated cellulose. Presently microfibrils with high lignin content have attracted increasing interest. Wood residues, like sawdust, are good candidates due to their abundancy and low price but the recalcitrant nature of the lignocellulose complex is an obstacle for the mechanical separation of microfibrils directly from wood. The purpose of this study was to investigate whether the mild sulfonation pretreatment of pine sawdust with sodium sulfite in neutral and mild alkaline conditions could enhance mechanical fibrillation in ultrafine wet grinding. Sawdust sulfonated at pH 7 and 9 resulted in a lignin sulfonation degree of 0.50.6% with a yield loss of 56%, approximately half of which was due to the dissolution of extractives from the initial content of 4.7% to 1.31.5%. Sawdust (with and without sulfonation) was pre-ground first in a twin-screw extruder, followed by ultrafine grinding with a friction grinder at a temperature of 80C. The viscosity and size distribution of the microfibrillated sample suspensions were determined. Additionally, the samples were filtered on a membrane, dried, and the mechanical properties of the sheets made from the samples were measured. The results showed that the sulfonation of softwood sawdust is a promising economic and environment-friendly method to produce microfibrillated cellulose with high lignin content (above 28%), having excellent strength properties, low viscosity, and fast dewatering rates. The sheets made from the sulfonated samples yielded an almost twofold increase in tensile strength and Young's modulus (100MPa and 77.5GPa, respectively) compared to the reference sample without sulfonation (52MPa and 4.3GPa) at an applied net grinding energy of 7MWh per ton. It was found that the size of the fibrils was at a similar level with and without sulfonation, but the bonding ability of the sulfonated samples was clearly better.

slurry rheology in wet ultrafine grinding of industrial minerals: a review - sciencedirect

slurry rheology in wet ultrafine grinding of industrial minerals: a review - sciencedirect

Wet ultrafine grinding has been increasingly used for production of ultrafine powders in various industries. It has been known that slurry rheology significantly influences the grindability of industrial minerals in wet ultrafine grinding. This review represents some previous work with respect to slurry rheology in ultrafine grinding. In this review, some methods for the characterization of the slurry rheology and some empirical equations modelling rheological behaviours of slurries were presented. The semiempirical model incorporating slurry rheology, solids concentration, particle size and slurry temperature was described. In addition, on-line measurement for the slurry rheology control was also discussed. In the case of ultrafine grinding, various parameters (such as solid concentration, particle size and distribution, particle shape, temperature, rotation and pH, use of dispersants), which affect the slurry rheology, have been described. It was revealed that the optimization of the rheological behaviours of slurry in ultrafine grinding could increase throughput, energy efficiency and product fineness as well. It is suggested to further study the mechanisms of slurry rheology in the presence of chemical dispersants in wet ultrafine grinding. It is desired to develop a model, which can represent a relation among slurry rheology, comminution parameters, amount of dispersant, energy efficiency and particle size characterization.

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