A cellulose dissolving process for its shaping

Abstract

A process and system thereof for dispersion based dissolution of solids including viscosity enhancing polymers and hard-to-wet solids whereby preferably cellulose pulp dissolution is provided that enhances dissolution of cellulose pulp leaving <0.1% undissolved particles in solvent system including phosphoric acid based solvent. The process of the present invention comprises contacting two separated stream of solids as compacted solids and solvent directly in the high shear zone of high speed mixer (HSM), to mix rapidly to provide fine dispersion and partial dissolution. This is followed by further mixing in a low speed mixer such as kneader for extended period to provide homogenous solution. The solution is forwarded to the shaping process, such as metering, filtration and extrusion.

Description

[0001] TITLE: A CELLULOSE DISSOLVING PROCESS FOR ITS SHAPING

[0002] FIELD OF THE INVENTION:

[0003] The present disclosure relates to a process for dispersion based dissolution of solids including viscosity enhancing polymers and hard-to-wet solids in solvent systems towards making articles starting from viscosity enhancing polymers and hard-to-wet solids including cellulose rich pulp obtained by digestion of wood or parts of plants. Particularly, the present disclosure relates to a process and a system thereof for dissolving such pulp into solvents allowing attainment of shaped products, such as fibers and films. Specifically, the present disclosure relates to such processes that strikes a balance between dissolution problems of such hard-to-wet polymers that is usually hindered by the first stage of pulp-solvent interaction resulting in structural changes in pulp particles including agglomeration and viscous gel-layer formation on surface that are difficult-to-break or dissolve, and alternatively also takes care of associated problems of solvent swelling that otherwise results in changes in hydrogen bonding, crystallization, molecular re-arrangement caused by solvent penetration unfavourable for the dissolution of particles. Advantageously, the present process is also able to circumvent long dissolution times and is free from low or high temperature requirement and complex machinery usually required to handle high viscosity solution and high power requirement.

[0004] BACKGROUND OF THE INVENTION:

[0005] The pulp is often available commercially in form of sheets. The process of shaping cellulose involves various techniques for dissolution of the pulp, shaping the solution, coagulation from the solution into desired shape, further shaping and freezing or consolidating the shape. Different solvents can be used such as caustic soda in the viscose or rayon process, tertiary amine (NMMO) in the lyocell process, phosphoric acid based solvents in the Boeel process.

[0006] Dissolution is often preceded by dispersion of the pulp as particles in the solvent system. This is often facilitated by grinding the pulp sheets into smaller particles of 0.1-10 mm prior to contacting the solvent, or in contact with the solvent prior to bringing to solvent conditions suitable for dissolution [Regenerated Cellulosic Fibers, Ed. Calvin Woodings, Woodhead Publishing, 2001], In spite of such size reduction, some particles may agglomerate into larger particles, and / or undergo solvent absorption that results in changes making further dissolution difficult especially at the core of particles, allowing only slow dissolution from the particle surface into the solvent which gets increasingly viscous with increasing content of dissolved cellulose in the solution. This increases the time, temperature and mixing requirements that increases the process costs. In some cases, this may be accompanied by degradation reaction that deteriorates the shaping process or the shaped product quality. Also, filtration of still undissolved particles is required prior to the shaping process. High undissolved content in the solution may demand large area of filter screen, or require frequent filter cleaning or replacements, and associated process interruptions. Further, there is loss of accompanying cellulose solution with the filtration residue, the loss increasing with finer filtration for improving filtrate quality. The escaping undissolved particle and gels may deposit in the narrow openings in shaping process, demanding cleaning and replacements, thus also causing process interruptions, or even land up in the shaped product and deteriorate the quality. For example, in case of shaping of pulp into fiber by solution spinning, the process may be interrupted by choking of the capillaries in the spinneret, requiring frequent replacement of spinneret as well as defects in the fibre product such as broken and fused fibers. Various researchers have worked on the shaping of the cellulose pulp. In "Viscose” process of dissolution into caustic soda, US2801998 describes that the process starts with slow steeping step of pulp into aqueous caustic soda, and pressing out of caustic soda into hardened alkali-cellulose. In the subsequent xanthation step to chemically convert cellulose into soluble xanthate using the toxic CS2 gas. The dissolution and ripening process even at the <10% cellulose content often requires more than 10 hr at sub-ambient temperatures. Removal of the undissolved cellulose as particles and gels in solution, is accomplished by filtration prior to shaping of solution into fibers or films. The filtration is carried out in several stages of increasing fineness, and determines the quality of the final solution. The loss of solution as filtration reject is a significant part of process cost. Cost of replacing choked filter is high and reuse is preferred.

[0007] A continuous “Lyocell” process for dissolving cellulose into tertiary amine (NMMO) was described (Diener and Raouzeos in Chemical Fibers International, Vol 49, March 1999. P.10) and involves a simple pre-conditioning contact of pulp and solvent, prior to kneader mixing with evaporation and self cleaning heat exchange surfaces. Solutions with cellulose content of up to 18% can be achieved, albeit at elevated temperature (~120°C) with process safety considerations.

[0008] Similar to the lyocell (and partly for viscose) processes for cellulose dissolution, even for dissolving other high molecular weight polymers such as polyvinyl alcohol powder, the traditional process is first slurrying and swelling in the liquid solvent at ambient temperature and only then bringing to dissolution temperature which is an inefficient, costly, capital intensive and time consuming process, where EP 0183285 describe methods where the first agitator facilitated slurrying step of polymer particles is followed by transfer the slurry to intensive mixing in extruder for dissolution at higher temperature. Similar two step dissolution concept with first stage as dispersion with little dissolution is described for polyethylene (US 4551296, US 4784820). In US5817801, an improvement with favorable environmentally profile for dissolving cellulose and shaping into very high strength cellulose fibers is described. The solvent used is based on phosphoric acid at cellulose concentration 14-18 wt% of solvent, air gap spinning is employed for fiber formation, coagulant is acetone, thus not reactive and hence potentially recoverable for reuse or recycling. The process temperatures are close to ambient, thus providing a safe process. However, in spite of trials with several solvent compositions solvent: cellulose ratio, and dissolution conditions, up to 1 wt.% of pulp remained undissolved when feeding pulp and solvent directly for intensive mixing in kneaders or twin screw extruders (TSEs) employing high shear forces that also favour size reduction. As well known in the practice of fiber making, the undissolved are often reduced by filtration that is difficult at the high dope viscosities, result in polymer and solvent loss as filtration reject, and requiring high filter change frequency for higher undissolved content. The escaping undissolved polymers tend to deposit on the spinneret capillaries and the fine filaments, causing filament breakages and thus product quality. The dissolution process needs to be improved to allow more complete dissolution of cellulose, to reduce their filtration load from the highly viscous solution, and associated losses. Though industrial researchers reported in above patents about the phosphoric acid-based solvents for dissolving the cellulose pulp, and shaping into automobile tire yams in an environmentally sustainable process, the process remains to be exploited commercially for more than 30 years.

[0009] The commercial processes “Viscose” and “Lyocell” for cellulose involve conditions and equipment for dissolution very different from each other, to provide acceptable level of dissolution in processes involving first a slow to moderate speed mixing for dispersion during initial contact of cellulose and solvent at conditions not favourable for dissolution, and dissolution leading to viscosity increase happen by subsequently bringing the good dispersion to conditions suitable for dissolution, i.e. substantially different temperature and solvent composition. Thus dissolution and excessive viscosity rise during the dispersion stage are avoided even at the longer dispersion time required due slow or moderate mixing conditions, and eventually lead to good dissolution during the subsequent dissolution step(s).

[0010] These known approaches of viscose and lyocell processes for solution hinge on identification of dispersion conditions largely free of dissolution for extended times, and cannot be directly extended to the rapidly interacting cellulose - phosphoric acid based solvent system. Here the phosphoric acid based solvent quickly dissolves the cellulose and becomes very viscous as high cellulose concentration is required for its liquid crystalline spinning. Due to this, it does not offer such possibility of distinct dispersion step largely free of dissolution over extended time without viscosity increase based on temperature and solvent concentration, and hence the inventors employed single-stage dispersion-dissolution, in kneaders or twin-screw extruders that offered high shear forces and potential of cellulose agglomerate size reduction, though with some extent of residual undissolved. Thus, complexities of such powder-solvent systems demand innovative mixing solutions for good dissolution, and remain to be found for achieving good dispersion of cellulose- phosphoric acid based system at the high cellulose concentrations.

[0011] In A review of polymer dissolution, Prog. Polym. Sci. 28 (2003) 1223- 1270, the authors teach that polymer dissolution in solvents is an important area of interest in polymer science and engineering because of its many applications in industry such as microlithography, membrane science, plastics recycling, and drug delivery, as polymers do not dissolve instantaneously, and the dissolution is controlled by either the disentanglement of the polymer chains or by the diffusion of the chains through a boundary layer adjacent to the polymer- solvent interface, in this review a general overview of several aspects of the dissolution of amorphous polymers as per the divisions under four sections highlighting are provided (1) experimentally observed dissolution phenomena and mechanisms reported to this date, (2) solubility behavior of polymers and their solvents, (3) models used to interpret and understand polymer dissolution, and (4) techniques used to characterize the dissolution process.

[0012] While the dissolution of hard-to-wet polymers / solids is usually hindered by first stage of pulp solvent interaction [Miller-Chou, Prog. Polym. Sci 28, 2003, p. 1223; Beatrice Swensson, PhD Thesis, Chalmers University, 2022, p.5, https: / / research.chalmers.se / publication / 528614 / file / 528614_Fulltext.pdf)] that result in structural changes in pulp particles including agglomeration and viscous gel-layer formation on surface that are difficult-to-break or dissolve, and alternatively, while such first stage of pulp solvent interaction may cause initial solvent swelling, changes in hydrogen bonding, crystallization, molecular re-arrangement caused by solvent penetration that may be unfavourable to dissolution of the particles, with dissolution therefore often demanding long dissolution times, often in combination with complex mixing equipment, and higher or lower temperatures, to handle high viscosity solution and high power requirement. There is still a long felt need in the art to explore for industrially viable facile processes for dissolution of viscosity enhancing polymers and hard-to-wet polymers at high concentrations that would be able to circumvent impenetrable agglomerates or viscous layer formation on particles, and overcome undissolved polymer particle formation otherwise required to be separated by filtration causing polymer loss together with loss in accompanying solvent. One potential way to address this is the high shear homogenizers.

[0013] For mixing in the conventional stirred vessels, the shear rates is typically <1000 / s, the rotation speed of rotor or stirrer is <1000 rpm, and tip speed is < 10 m / s. In extruders, the very low screw-barrel screw-screw gaps help achieve similar shear rates up to 1000 / s, inspite of the very low rotation speed < 1000 rpm, and very low tip speeds. On the other hand, the so called high-shear homogenizers operate at very high shear rates of 20,000-100,000 / s, achieved by rotational speeds of 5000-20,000 rpm, tip speeds of 10-50 m / s, and (Chem. Engg. and Processing: Process Intensification, Vol 57-58, p 25, 2012), and are considered especially suited for solid-liquid dispersions. These often comprise a rotor with a stator close-by, and can be operated in batch mode or in-line (https: / / en.wikipedia.org / wiki / High- shear mixer). In batch mode, these are operated dipped- in in filled tanks, causing and facilitated by internal circulation in the tanks. This internal circulation is only possible if the dispersion is not accompanied by extreme viscosity rise due to simultaneous dissolution of high concentration of high molecular weight polymer. In the in-line mode, the two streams are continuously worked-in, and mixture is continuously discharged. When powder dispersion is required, either its pre-prepared slurry is pumped to the inlet liquid line, or solvent-free and free-flowing powder can be worked-in using powder induction systems where powder is pulled-in (https: / / www.pharmtech.com / view / batch-high-shear-mixers). In case of desired dispersion of high loading of powder by generating vacuum by employing high liquid rate in a ventury in the inlet pipe or into the sub-surface high-shear zone of filled mixer, where multiple re- circulatory passes of the mixture (https: / / inos.in / powder-induction / , https: / / www.mixers.com / resources / mixing- technology-reports / optimize-powder-inj ection-in-your-batch- mixer / ) help achieve the high velocity required for generating sufficient pull. However, such powder induction and high velocities with multiple recirculation are not permissible if the dispersion is accompanied by significant dissolution leading to very high viscosity increase during the substantial time of multiple passes. When the desired polymer- solvent system involves dispersion with viscosity-enhancing rapid-dissolution, only single or limited passes may be permissible before large viscosity rise. This is then unable to generate sufficient vacuum for sufficient polymer induction for achieving high polymer concentration. Thus, if the dispersion in high speed mixers is accompanied by simultaneous rapid and extreme viscosity enhancing dissolution, the dispersion may need to be achieved with alternative way of solid powder feeding. Flow of low density solid powders at high feeding rates is further challenged by their non-free flowing nature as well as bridge formation at transfer necks of vessels that leads to choking. Therefore, the feed methods rely on solids being carried by drag of large amount of air or the dispersion medium liquid. One alternative method is use of crammer feeders for feeding solids to extruders (https: / / nfm.net / crammer-feeder / , https: / / www.ptonline.com / articles / extrusion-how-hopper-crammers-can-help- feeding), but are not reported for feeding in high speed mixers. Due to low rotational and tip speeds in extruders, though mixing of systems such as US ‘801 suffer on account of slow dispersion leading to clumps and undissolved solids, they do not suffer from liquid splashing, and related role of crammer feeders is not known. On the other hand, the blade speeds in high speed mixers (HSM) are much higher and responsible for splashing, including towards the feed pipes or columns, thereby forming clumps due to pre-contact in those feeding regions for hard-to-wet powders. Thus learning’s or methods from TSE (twin screw extruder) feeding systems are not directly extendable to HSM where there is additional challenge posed by such splashing resulting in polymer-solvent contact prior to entering the HSM, and thus leading formation forming sticky agglomerates and clumps with impenetrable layers, that remain undispersed and undissolved and also cause choking in feeding system. Therefore it is desired to avoid such polymer-solvent contact prior to entering the high shear zone of the HSMs.

[0014] US4390284 and US5368385 disclose methods for preparing a homogeneous dispersion of a hard-to-wet powder, by limiting the powder-solvent contact to the spray mixing zone at the bottom of the delivery apparatus that then feeds into the high shear homogenizer for dispersion. However, the polymer-solvent contact in the delivery apparatus is only minimized, and not eliminated as the downwards moving polymer and solvent sprays do contact in the delivery apparatus, and additionally the container walls are maintained wet with the downward flowing solvent introduced at top of apparatus through multiple nozzles or other means. The inventors of these prior arts themselves realized finite chances of clump formation and wall deposits depending on intimacy of such contact that forms sticky layered particles / agglomerates on contact. Deposition of such sticky particles on wet stationary wall and surfaces around the feed and discharge openings can build up, leading to potential of line choking, especially when high volume fraction of solids is desired. This demands additional complication of wiping devices for the wet wall and is provided. The delivery apparatus itself is thus quite complex claiming incorporation of 95% powder, but industrial implementations requires a fool proof and maintenance free yet inexpensive process. Thus simpler solution is required so that without contact with the solvent, large concentrations of powder can be introduced directly into high shear homogenizer at its high shear zone near the blades. Further, demands of alternative polymer-solvent systems for extent of contact avoidance may be more stringent depending on the desired solids content, relevant characteristics like stickiness, wetting and dissolution.

[0015] Reference is also invited to US11753482B2, directed to a spinning dope composition production system comprising: a homogenization unit adapted for receiving cellulosic pulp material and alkali solution, comprising a high shear mixing means for homogenizing cellulosic pulp material in alkali solution, for < 120 sec, preferably less than 15 sec; and a dissolution unit adapted for receiving the homogenized material and mixing for a longer period of 5-30 min. While the powder pulp and the cold alkali for dissolving the pulp are fed separately to the system, the disadvantage of the process is that prior to introducing into the high shear mixer, the solid is first contacted with the solvent for pulp slurry preparation without employing high shear at low alkali concentration not favorable to dissolution, thus conceptually similar to the commercial preparation of viscose and lyocell processes that allow employing solid-liquid pre-contact for pulp slurry preparation under solvent conditions not favorable to dissolution. Alternatively, they employ brief but finite pre-contact of cellulose and solvent in a feeding device that is a hopper and a slow intermeshing twin agitator. The limitations of such pre-contact in feeding devices in preceding paragraph for ‘385 for systems that can undergo rapid particle-surface dissolution at the existing low speed conditions, are that they lead to sticky product and agglomerates that can form clumps to remain undissolved, or form deposits and cause choking during transfer to the feeding device, in the feeding device, or during transfer to the high shear mixer.

[0016] Hence while several mixing-feeding options for dissolution of solids such as of viscosity enhancing polymers and hard-to-wet solids in solvents are known, there is still a need in the art to explore for suitable processes and systems thereof for rapid dispersion based dissolution of such solids that would be free of any solid-solvent interaction or feed blockage outside said high shear region of HSM so as to avoid deposits building up on feeder walls (or associated moving or rotating internals) and to also avoid formation of bridge by such deposits that would otherwise choke the feed flow or form clumps which then fall into the mixture undergoing high shear thereby escaping the mixer after only partial dispersion to remain as unwanted dry powder agglomerates to be noticed in the viscous discharge, and also upon following standing or moderate shear dissolution step.

[0017] OBJECTS OF THE INVENTION:

[0018] The primary objective of the present invention is to provide a process for dissolution of solids and system for delivering solids to high speed mixer for its dispersion in a liquid also being injected into the same mixer so that the solid-solvent contact directly in the high shear region of the high speed mixer. Another object of the present invention is to provide said process for dissolution of solids that are not free flowing and said system for delivering solids including as compacted powder directly to high speed mixer by continuously advancing it towards the mixer cavity significantly along the axis of rotation of the blades of the high speed mixer.

[0019] Another object of the present invention is to provide for said process for dissolution of solids / polymers that are hard-to-wet including cellulose pulp and said system of delivering solids as compacted powder directly to high speed mixer by continuously advancing the compacted-powder in a cylindrical or other shaped cross-section barrel, while the compacted powder substantially filling this barrel cross-section at least at the entry to the HSM cavity, also continuously wiping the barrel surface, towards the mixer cavity significantly along the axis of rotation of the blades of the high speed mixer

[0020] Another objective is to provide for said process for solids that are viscosity enhancing on contact with the solvent and said system integrated to a mill for powdering the solid, forwarding the thus powdered solid with air to a cyclone separator for air extraction and use an solid extrusion screw to collect, compress and advance the solid through the extrusion barrel to the high speed mixer.

[0021] It is another objective of the present invention to provide for a system for delivering polymer particles / powder to a high speed mixer for its dispersion in a liquid also being injected into the same mixer so that the polymer-solvent contact directly in the high shear region of the high speed mixer. Another object of the present invention is to provide for process for dispersion of solids that are easily dissolved on contact with solvent to generate high viscosity surface, sticky clumps, deposits and agglomerates.

[0022] Another object of the present invention is to provide for process for dispersion of solids at high volume % of the solvent.

[0023] Another object of the present invention is to provide for process for dispersion of solids including cellulose, PVA (polyvinyl alcohol), PVAc (polyvinyl acetate), PPTA (polyphynylene terephthlamide) into a solvent.

[0024] Yet another objective of the present invention is to provide for a process for cellulose pulp dissolution while maintaining and environmentally friendly process with no emissions and free of any involvement of elevated temperatures.

[0025] Still another objective of the present invention is to provide for a process for quick dissolution of cellulose.

[0026] These and other objects and advantages of the present subject matter would be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which preferred embodiments of the present subject matter are illustrated.

[0027] SUMMARY OF THE INVENTION

[0028] Thus according to the basic aspect of the present invention there is provided a process for dispersion based dissolution of solids including viscosity enhancing polymer and hard-to-wet solid in solvent systems comprising: involving a high speed mixer (HSM) adapted for high shear mixing; step of dispersion for facilitating dissolution of said solid of bulk density >0.1 g / cc including non-particulate solids in said solvent systems carried out selectively firstly only in the high shear zone of said high speed mixer including the high speed rotating impeller blades by continuously feeding separately and directly in said high shear zone said solid for dispersion in a plug form and said solvent system thereby enabling said rotating impeller blade based scrapping of the said plug form solid feed for its rapid dispersion and wetting in said solvent systems restricted within said high shear zone of the mixer only under action of said high shear mixing, free of any solidsolvent interaction or feed blockage outside said high shear region in said mixer and avoiding difficult to dissolve agglomeration and / or viscous gel layer formation on the solid thereby facilitating rapid dispersion based dissolution of solids.

[0029] Preferably said process is provided wherein said step of feeding separately and directly in said high shear zone said solid for dispersion in said plug form preferably at feeder-mixer interface includes feeding said plug form of the compacted solid and said solvent system through channelizing the compacted solid feed in plug form and said solvent system separately and directly into said high shear region of the high shear mixer avoiding any premixing prior to subjecting to the high shear mixing.

[0030] According to another preferred aspect of the present invention there is provided said process wherein said step of channelizing the feed into said high shear region of the high speed mixer include selectively (a) feeding the compacted plug form solid and solvent systems from separate sources directly into the high shear region (b) feeding said plug form of compacted solids sourced from powdery / particulates in agglomerated compacted form as the plug form compacted / compact solid in its precompacted form or as on-line compacted solid feed separately from the solvent system from separate sources, enabling selective front face scrapping / slicing of the fed plug form solid by said rotating impeller blades for said controlled disintegrating of said solids for rapid dispersion into the solvent system.

[0031] Preferably in said process wherein said plug form compacted solid feed during dispersion process is supplied for filling the entire feeder cross-section at least at coupling to the high shear zone to avoid solvent splash from mixer into feeder sections and ensuring complete solid particulate dispersion and wetting within said high shear zone of the high shear mixer.

[0032] According to another preferred aspect of the process wherein said plug form compacted solid is introduced in said high shear zone of the high speed mixer through separate feeder barrel for entry of solids and its required necessary compression based compaction and extrusion as solid plug into said high shear zone of the mixer by piston-press or extrusion feeding such as crammer feeder; said solvent system is introduced through plurality of apertures for injecting solvent system / liquid therefrom into the high shear zone; co-operating high shear mixer (HSM) zone / cavity at outlet end of the barrel equipped with high-speed impeller spanning said HSM cavity for scrapping the extruded and contacting front of the compacted solid plug in said high shear region of said high shear mixer (HSM) for directly contacting with injected liquid / solvent in said high shear mixer (HSM) zone, alongwith simultaneous solid extrusion through barrel continuously wiping the barrel internal surface thereby favouring unrestricted passage of solid and clump / agglomerate free feeding and dispersion of solids in liquids.

[0033] More preferably in said process wherein said process adaptive to solid extruded as compacted plug for interaction with liquid / solvent in HSM zone and in being free of integrated stator of rotor-stator system favours said unrestricted passage of dispersion slurry out of the high shear chamber by avoiding large flow direction change past the conventionally integrated stator or by employing conical stator with axial discharge. According to another preferred aspect of the process wherein said high-speed impeller is a flat-blade type impeller rotating at > 3000 rpm favouring scrapping of the thus extruded solid plug front at thickness levels of < 20 microns.

[0034] Preferably in said process wherein said piston or extruder in the feeder barrel continuously advances the compacted powder plug directly into HSM zone / cavity along the axis of rotation of the impeller blades that also continuously wipes the barrel surface, and wherein the cooperation between the piston and the rotor blades enables slicing off the bottom surface of the compacted solid plug every milliseconds thereby continuously renewing the plug surface for wetting and dispersion by liquid / solvent avoiding splashing of solvent towards barrel wall as barrel is filled with impenetrable plug moving downwards free of wetting of barrel and even when wetted is immediately wiped clean by the advancing plug.

[0035] More preferably in said process wherein said feeder barrel is integrated with a powdering mill for powdering the solid, through cyclone separator for air based extraction in the cyclone, fitted with an extrusion screw internally or external to the cyclone, to collect, compress and advance the powdered solid through the extrusion screw to said barrel and onward to said high shear mixer.

[0036] According to another preferred aspect of the present process wherein said solid is hard-to-wet solid or sticky solids and / or are solids devoid of free flow with tendency to form insoluble lumps and / or impenetrable viscous layer including polymer cellulose, PVA (polyvinyl alcohol), PVAc (polyvinyl acetate), PPTA (polyparaphenylene terephthlamide) for said dispersion / dissolution in liquid thereby enhancing the viscosity of liquid upon contact, and, said liquid is a solvent including water with the polymer being soluble in solvent at appropriate conditions. Preferably said process is provided wherein the solid for dispersion at high volume % of the solvent involves cellulose pulp of density 0.5-0.9 g / cc, at > 10 vol% in solvent of density 0.9-2 g / cc, which is dispersed and dissolved on contact with liquid solvent system in said high shear mixing zone of said high speed mixer, to generate high viscosity dispersion preferably >10 Poise in < 10 sec after contact, free of sticky clumps, deposits and hard insoluble agglomerates, and wherein said solid dispersion for dissolution in liquid is suitable for enabling dissolution, chemical derivatization / modification including cellulose to ethers or esters and / or shaping into articles including fibers.

[0037] More preferably said process includes subjecting the thus dispersed solids in solvent system to a step of dissolution in a kneader or extruder including twin screw extruder for making spinning dope followed by shaping for fiber making in textiles, incorporating in polymeric matrix to make composites, including with rubber for making tyres.

[0038] Preferably said solvent system includes acidic oxide based solvent system striking a balance between dispersion and dissolution of cellulose polymer solids in select solvent system, with said select solvent being precooled to 0-20 °C comprising blend of at least two of polyphosphoric acid, orthophosphoric acid and phosphorus pentoxide with P2O5 content of 65-80%, with said select polymer solid including feed cellulose pulp rich in alfa-cellulose content.

[0039] Advantageously, in said process wherein dissolution of polymeric solids in the solvent system is substantially complete or leaves < 0.1% undissolved polymer particles reducing the filtration load for viscous solution and associated losses during further processing including shaping or chemical modification. Preferably in said process wherein the polymeric solid include cellulose and generates environmentally friendly cellulose pulp dissolution that is free of emissions, free of involvement of elevated temperatures, also allowing easy recovery of reagents.

[0040] According to another aspect of the present invention there is provided a system adaptive to said process for dispersion based dissolution of solids including viscosity enhancing polymers and hard-to-wet solids in solvent systems comprising: a high speed mixer (HSM) including a high shear region including a high speed rotating impeller blade means (R) defining said high shear region for mixing; said high shear region of the high speed mixer (HSM) having feed inlet means (FC / FB) for direct operative connect to supply said solvent system (SI) and said plug form solid therein selectively in (i) dispersible solid supply through operative connect to a solid source (SP) for feeding in feeder barrel (FC / FB) towards generating said plug including compacted solid into high shear region of said high speed mixer (HSM) and (ii) a cooperative feed barrel (FC / FB) connect to said high shear region for supply of said plug form including compacted solid directly into said high shear region for the operative impeller blade (R) to scrap the plug form solid in said high shear region for its rapid dispersion and wetting in said solvent systems restricted within said high shear zone of the mixer only under action of said high shear mixing, free of any solid-solvent interaction or feed blockage outside said high shear region in said mixer and avoiding difficult to dissolve agglomeration and / or viscous gel layer formation on the solid thereby facilitating rapid dispersion based dissolution of solids.

[0041] Preferably in said system wherein said feed barrel (FC / FB) is integrated with a powdering mill (M) for powdering the solid, and carrying to cyclone separator (C) in connection for air based extraction in the cyclone (C) fitted internally or externally with an extrusion screw (ES) to collect, compress and advance the powdered solid through the extrusion screw to said barrel and onward feed into said high shear zone of said high shear mixer.

[0042] These and other objects and advantages of the present invention would be apparent to a person skilled in the art after consideration of the following detailed description by taking into consideration the accompanying drawings in which preferred embodiments of the present subject matter are illustrated.

[0043] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying figures / drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein are not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.

[0044] DETAILED DESCRIPTION OF THE INVENTION

[0045] As discussed hereinbefore, the present invention provides for a process and a system for dispersion based dissolution of solids including viscosity enhancing polymers and hard-to-wet solids in solvent systems comprising: involving a high speed mixer (HSM) adapted for high shear mixing; involving step of dispersion for facilitating dissolution of said solid of bulk density >0.1 g / cc including non-particulate solids in said solvent systems carried out selectively only in the high shear zone of said high speed mixer including the high speed rotating impeller blades by feeding separately and directly in said high shear zone said solid for dispersion in a compacted form and said solvent system thereby enabling said rotating impeller blade based scrapping of the compacted solid feed for its rapid dispersion and wetting in said solvent systems restricted within said high shear zone of the mixer only under action of said high shear mixing.

[0046] The process of the present invention is advantageously free of any solid-solvent interaction or feed blockage outside said high shear region in said mixer and could thus avoid difficult to dissolve agglomeration and / or viscous gel layer formation on the solid thereby facilitating rapid dispersion based dissolution of solids.

[0047] EXAMPLES:

[0048] The following form of cellulose was used:

[0049] 1) Free flowing granules of dia ~ 1 mm, bulk density ~ 0.23 g / cc

[0050] 2) Pulp sheet particles: Dissolving grade pulp sheet (1 mm thick, density ~ 0.7 g / cc) cut into 7 mm X 25 mm

[0051] 3) Powder: Pulp sheet particles as above, ground in a dry mill to short fibers with bulk density of - 50 g / L

[0052] The solvent used was a mixture of phosphorus pentoxide and 85% orthophsphoric acid, and solvent strength was 105% expressing all phosphorus as H3PO4. The solvent density was 1.92 g / mL. Cellulose concentration of 4-15% in solvent was used.

[0053] Example 1

[0054] A single pass version of laboratory test system for high shear homogenization is available (https: / / www.ikaprocess.com / en / Products / Solid-liquid-mixers-powder-cph- 28 / MHD-continuous-csb-MHD / ) where the falling solid in feeding or pre-mixing chamber, mounted directly above the bottom-mounted high-shear rotor-stator system, contacts the liquid injected through multiple apertures on the walls of the pre-mixing chamber, on way to the rotor-stator mixer. It was found that for this system especially for solid: liquid feed rate increasing beyond -5 wt% for various solid cellulose feed forms (powder, flakes, free-flowing particles), the falling cellulose particles / agglomerates gets wetted in the pre-mixing chamber with the phosphoric acid based solvent, and either deposits and builds up on the wall (and on the rotating internals when used to intensify particle feeding) to form bridge and then chokes the flow, or forms clumps that fall into the mixture undergoing high shear and escape the mixer after only partial dispersion as dry powder agglomerates that can be noticed in the discharge, even after standing for 4 hours.

[0055] Example 2

[0056] In an adaptation of this and to overcome the above hurdle, feeding only the solid cellulose powder samples were provisioned (dropped) into the cylindrical feeding chamber based system of the present invention mounted on top of a high speed mixer comprising bottom mounted high-speed impeller of the flat-blade type (https: / / www.rossicarlosrl.com / prodotto / flat-blade-impeller / ?lang=en) spanning the mixer cavity.

[0057] Liquid injection was not done through the cylindrical feeding chamber, but the liquid was injected independently and directly into the high-shear zone from bottom, and a high-speed flat-blade impeller spanning the entire mixer cavity was used without a stator to avoid restricting the discharge with the blades of the impeller rotated at 18,000 rpm (Figure 1). The splashing and vortex liquid from the high shear chamber into the feeding chamber was sufficient to wet the feeding chamber walls, wetting the falling cellulose particles / agglomerates for the powder feed at 15wt.% of the liquid, forming deposits on the wall that grow and form a bridge and clumps that later choke the flow but initially fall into the mixture undergoing high shear and yet escape the mixer after only partial dispersion, as dry powder agglomerates (‘hard’ clumps) can be noticed as dense white spots in the discharge even after standing for 4 hours as is represented through Figure 3 a. This establishes that for certain hard-to-wet and sticky mass forming polymer- solvent combinations at high polymer concentrations, it is not feasible to continuously even feed in a high shear mixer. Such limitation is more severe for powders on account of the low bulk density.

[0058] Example 3

[0059] Further to the above, an adaptation shown in Figure 2 where compacted powder (obtained by compressing the fine powder, such as with a piston) was pre- filled in the cylindrical feeding chamber. The impeller rotation as well as the solvent feeding was started at 5 g / s and simultaneously the cellulose pre-fdled powder was advanced from the feeding chamber by moving a piston pushing the compressed powder plug at a rate targeting a cellulose concentration of 15 wt.% of the solvent. Rotating at 18000 rpm, the blades of the impeller scrapped the powder cellulose of thickness < 10 microns, dispersed in the solvent and discharged by the centrifugal force of the impeller rotation. The discharge after 10 min standing was largely fine wetted cellulose pulp fibers, wetted and separated with the solvent, and no clumps could be seen. Some gel like shadow portions can be seen as soft gels comprising wet fibers as in Figure 3b that disappeared on mild shearing of the slurry between glass plates, partly representing the process of kneading for dissolution.

[0060] The compacted powder could be provided in alternative ways, such as continuously being compressed and conveyed using a solid extrusion (or compression) or briquetting screw as shown in Figure 4.

[0061] Such crammer feeding when employed in conjunct with HSM was found to be synergistic to avoid the wetting of solid feeder walls by splashing, thereby advantageously allowing solid-liquid contact only at the feeder-mixer interface and disallowing any solid-liquid contact prior to contact in high shear zone, leading to efficient dispersion. Such is not the usual objective to employ crammer feeders for feeding in high speed mixers as they are usually known to be employed for feeding solids of low density powders to Twin Screw Extruders to avoid bridge formation / choking at transfer necks of vessels and the low speeds therein do not lead to splashing issues anyway.

[0062] The powder can be continuously availed by processing the pulp sheet or its parts in a powdering mill such as hammer mill. The powder output with the conveying air can be passed through a cyclone separator to provide feed to the solids compressions screw. As shown in Figure 4, the screw of the crammer feeder to mixer could be integrated into the cyclone separator to facilitate discharge from the cyclone separator.

[0063] BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The disclosure may be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows:

[0065] Figure 1 illustrates the process for dispersion of solids (solid powder-SP) in a liquid by dropping the solid directly onto the mixture undergoing mixing when the liquid is being injected in the same mixer from a separate inlet (SI), and also preferably illustrates cellulose powder or particles that are continuously fed through the solid feeding chamber (FC) / feeder barrel (FB) mounted on top of the high speed mixer (HSM) and once the powder falls on to the mixture, it is drawn into the fluid in the mixer by the rotor (R), the fluid itself introduced from the bottom, however minor splashing liquid from the mixer onto the feeder wall (FW), wets the wall, providing for cellulose sticking to the splashing solvent / mixture and releasing viscous slurry (VS) through large opening by centrifugal force, into moderate mixer including kneader. Figure 2 illustrates the process for dispersion of solids in a liquid by compacting and advancing compacted solid by a piston (P) through a feeder chamber (FC) / feeder barrel (FB) onto the mixture under mixing when the liquid is being injected in the same mixer from the bottom of the barrel such that the solid and liquid contact directly in the high shear region of the mixer near the mixer blade, and, also demonstrates that the compacted plug by the advancing piston continuously pushes down very fine layers (~10 micron) every millisec in immediate (not apriori) contact with the liquid as sliced by the blade, while the bottom surface of the plug is continuously getting renewed not allowing splashing of solvent upwards to the feeder barrel wall (FW) as barrel is filled with downward moving compact impenetrable plug, and disallowing wetting of barrel (= feed pipe) walls, which even if accidentally wetted such as during process startup, is immediately wiped clean by the advancing plug;

[0066] Figure 3 represents a 5 cm x 5 cm real space image of the slurry obtained by feeding into high shear mixer at 18,000 rpm a powdered cellulose at 15 wt.% of the phosphoric acid based solvent introduced into the same mixer from bottom and the nature of desired dispersion of the solid in the solvent system in terms of its targeted final dissolution in the solvent (a) when powder is simply dropped into the cylindrical feeding chamber (b) when a compacted plug of cellulose powder is gradually lowered through the feeder barrel by employing a piston. While when following (a) powder is simply dropped into the cylinder feeding chamber, and inspite of its high shear mixing, (‘hard’ clumps) can be noticed as dense white spots in the discharge even after standing for 4 hours as is represented through Figure 3a. On the other hand, when following the present advancement (b), the compacted plug of cellulose powder is interacted with the high shear mixer blades, the rapid particulate dispersion into the solvent even at 15 wt. % level clearly avoided the hard clump formation and only some soft gels comprising wet fibers as in Figure 3b are seen that disappeared on mild shearing of the slurry between glass plates, partly representing the process of kneading for dissolution. The selective co-action in plug / compacted solid and mixer blade interaction and co-action in high shear zone of the high shear mixer for benefitting the required dispersion for facilitating the dissolution is thus well demonstrated. It is also relevant to note that the plug-shaped solid entry covering the entire internal dimensions of feed barrel at the high shear zone interaction with the solvent, blocks the unwanted splashing of the feed and related feed complexities apart from keeping the internal surface of the barrel clean and with less maintenance costs.

[0067] Figure 4 illustrates the process towards continuous implementation of powdering the polymer solid including cellulose in a mill (M), extracting the air in the powdered product using a cyclone, and using a solid extrusion screw (ES) integrated into the cyclone (C) to compress the powder and advance it through the screw barrel.

[0068] The following comparative table further compares the various combinations of solid feeding and mixing processes and their respective dispersion performances in relation to target end dissolution of solids in solvent systems:

[0069]

[0070] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.

[0071] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a",” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and / or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0072] It should also be noted that in some alternative implementations, the functions / acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality / acts involved.

[0073] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0074] The present disclosure preferably discloses a process for cellulose pulp dissolution in phosphoric acid based solvent, striking a balance between dispersion and dissolution of polymer solids in select solvent system, with said select solvent being precooled to 0-20 °C comprising blend of at least two of polyphosphoric acid, orthophosphoric acid and phosphorus pentoxide with P2O5 equivalent content of 65-80%, with said select polymer solid including feed cellulose pulp rich in alfa-cellulose content.

[0075] The present process preferably comprises of contacting two separated stream of cellulose pulp and said pre-cooled solvent directly in the high shear zone of high speed mixer (HSM), to mix rapidly to provide fine dispersion and partial dissolution. The discharge of the high speed mixer of thus dispersed solids in solvent system is preferably forwarded to a step for dissolution in a kneader followed by metering, filtration and extrusion for shaping and for fibre making for textiles, for incorporating in polymeric matrix to make composites, including with rubber for making tyres. The kneader is preferably equipped with vacuum vent to enable removal of the entrapped air.

[0076] The first step of dispersion-dissolution preferably of dispersion is carried out in a high-shear zone of high-speed mixer equipped with a rotor impeller such as flat blade type impeller operating at said high speed. The apparatus and feeding of the solid and liquid separately are so configured that the solid as compacted solid and liquid come into contact directly in the high shear zone of the HSM with the impeller blades scrapping the compacted solid feed for its rapid dispersion and wetting in said solvent systems. It is desired that entire volume of HSM experiences the intense mixing, free of any dead zones, and that particles have no opportunity to escape the high-shear mixing.

[0077] The temperature and composition of input or feed raw materials is varied for rendering it suitable for the subsequent step of dispersion-dissolution. The feed cellulose pulp is preferably rich in alfa-cellulose content and could preferably be easily dispersing type. It may be varied with regard to its degree of polymerization for required solution characteristics. The solvent may be precooled to 0-20 deg C. The next step of cellulose pulp dissolution is carried out in a low speed mixer for an extended time where the dissolution continues and viscosity rises many fold. The low speed mixer is preferentially be a kneader operating at 0-40 deg C under vacuum for deaeration. The kneader may be equipped with a conveying extruder to forward the high viscosity solution to the shaping process. This discharge process may be designed to not break the vacuum in the kneader.

[0078] The discharged high viscosity cellulose solution may be optionally heated to facilitate the shaping process, and then forwarded to metering pump, filtering, and shaping die. In case of fiber production, the shaping die may constitute of plurality of openings, and its extrudate may be lead to coagulation bath as described in US5997790.

[0079] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system / component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations, which fall within the scope of the present subject matter.

Claims

Claims:

1. A process for dispersion based dissolution of solids including viscosity enhancing polymer and hard-to-wet solid in solvent systems comprising: involving a high speed mixer (HSM) adapted for high shear mixing; step of dispersion for facilitating dissolution of said solid of bulk density >0.1 g / cc including non-particulate solids in said solvent systems carried out selectively firstly only in the high shear zone of said high speed mixer including the high speed rotating impeller blades by continuously feeding separately and directly in said high shear zone said solid for dispersion in a plug form and said solvent system thereby enabling said rotating impeller blade based scrapping of the said plug form solid feed for its rapid dispersion and wetting in said solvent systems restricted within said high shear zone of the mixer only under action of said high shear mixing, free of any solidsolvent interaction or feed blockage outside said high shear region in said mixer and avoiding difficult to dissolve agglomeration and / or viscous gel layer formation on the solid thereby facilitating rapid dispersion based dissolution of solids.

2. The process as claimed in claim 1 wherein said step of feeding separately and directly in said high shear zone said solid for dispersion in said plug form preferably at feeder-mixer interface includes feeding said plug form of the compacted solid and said solvent system through channelizing the compacted solid feed in plug form and said solvent system separately and directly into said high shear region of the high shear mixer avoiding any premixing prior to subjecting to the high shear mixing.

3. The process as claimed in anyone of claims 1 or 2 wherein said step of channelizing the feed into said high shear region of the high speed mixer include selectively (a) feeding the compacted plug form solid and solvent systems fromseparate sources directly into the high shear region (b) feeding said plug form of compacted solids sourced from powdery / particulates in agglomerated compacted form as the plug form compacted / compact solid in its pre-compacted form or as online compacted solid feed separately from the solvent system from separate sources, enabling selective front face scrapping / slicing of the fed plug form solid by said rotating impeller blades for said controlled disintegrating of said solids for rapid dispersion into the solvent system .

4. The process as claimed in anyone of claims 1 to 3 wherein said plug form compacted solid feed during dispersion process is supplied for filling the entire feeder cross-section at least at coupling to the high shear zone to avoid solvent splash from mixer into feeder sections and ensuring complete solid particulate dispersion and wetting within said high shear zone of the high shear mixer.

5. The process as claimed in anyone of claims 1-4 wherein said plug form compacted solid is introduced in said high shear zone of the high speed mixer through separate feeder barrel for entry of solids and its required necessary compression based compaction and extrusion as solid plug into said high shear zone of the mixer by piston-press or extrusion feeding such as crammer feeder; said solvent system is introduced through plurality of apertures for injecting solvent system / liquid therefrom into the high shear zone; co-operating high shear mixer (HSM) zone / cavity at outlet end of the barrel equipped with high-speed impeller spanning said HSM cavity for scrapping the extruded and contacting front of the compacted solid plug in said high shear region of said high shear mixer (HSM) for directly contacting with injected liquid / solvent in said high shear mixer (HSM) zone, alongwith simultaneous solid extrusion through barrel continuously wiping the barrel internal surface thereby favouring unrestricted passage of solid and clump / agglomerate free feeding and dispersion of solids in liquids6. The process as claimed in anyone of claims 1-5 wherein said process adaptive to solid extruded as compacted plug for interaction with liquid / solvent in HSM zone and in being free of integrated stator of rotor-stator system favours said unrestricted passage of dispersion slurry out of the high shear chamber by avoiding large flow direction change past the conventionally integrated stator or by employing conical stator with axial discharge.

7. The process as claimed in anyone of claims 1 -6 wherein said high-speed impeller is a flat-blade type impeller rotating at > 3000 rpm favouring scrapping of the thus extruded solid plug front at thickness levels of < 20 microns.

8. The process as claimed in anyone of claims 1-7 wherein said piston or extruder in the feeder barrel continuously advances the compacted powder plug directly into HSM zone / cavity along the axis of rotation of the impeller blades that also continuously wipes the barrel surface, and wherein the cooperation between the piston and the rotor blades enables slicing off the bottom surface of the compacted solid plug every milliseconds thereby continuously renewing the plug surface for wetting and dispersion by liquid / solvent avoiding splashing of solvent towards barrel wall as barrel is filled with impenetrable plug moving downwards free of wetting of barrel and even when wetted is immediately wiped clean by the advancing plug.

9. The process as claimed in anyone of claims 1-8 wherein said feeder barrel is integrated with a powdering mill for powdering the solid, through cyclone separator for air based extraction in the cyclone, fitted with an extrusion screw internally or external to the cyclone, to collect, compress and advance the powdered solid through the extrusion screw to said barrel and onward to said high shear mixer.

10. The process as claimed in anyone of claims 1-9 wherein said solid is hard-to-wet solid or sticky solids and / or are solids devoid of free flow with tendency to form insoluble lumps and / or impenetrable viscous layer including polymer cellulose, PVA (polyvinyl alcohol), PVAc (polyvinyl acetate), PPTA (polyparaphenylene terephthlamide) for said dispersion / dissolution in liquid thereby enhancing the viscosity of liquid upon contact, and, said liquid is a solvent including water with the polymer being soluble in solvent at appropriate conditions.

11. The process as claimed in anyone of claims 1-10 wherein the solid for dispersion at high volume % of the solvent involves cellulose pulp of density 0.5 -0.9 g / cc, at > 10 vol% in solvent of density 0.9-2 g / cc, which is dispersed and dissolved on contact with liquid solvent system in said high shear mixing zone of said high speed mixer, to generate high viscosity dispersion preferably >10 Poise in < 10 sec after contact, free of sticky clumps, deposits and hard insoluble agglomerates, and wherein said solid dispersion for dissolution in liquid is suitable for enabling dissolution, chemical derivatization / modification including cellulose to ethers or esters and / or shaping into articles including fibers.

12. The process as claimed in anyone of claims 1-11 includes the thus dispersed solids in solvent system to a step of dissolution in a kneader or extruder including twin screw extruder for making spinning dope followed by shaping for fiber making in textiles, incorporating in polymeric matrix to make composites, including with rubber for making tyres.

13. The process as claimed in anyone of claims 1-12 wherein said solvent system includes acidic oxide based solvent system striking a balance between dispersion and dissolution of cellulose polymer solids in select solvent system, with said select solvent being precooled to 0-20 °C comprising blend of at least two ofpolyphosphoric acid, orthophosphoric acid and phosphorus pentoxide with P2O5 content of 65-80%, with said select polymer solid including feed cellulose pulp rich in alfa-cellulose content.

14. The process as claimed in anyone of claims 1-13 wherein dissolution of polymeric solids in the solvent system is substantially complete or leaves < 0.1% undissolved polymer particles reducing the filtration load for viscous solution and associated losses during further processing including shaping or chemical modification.

15. The process as claimed in claims 1-14 wherein the polymeric solid include cellulose and generates environmentally friendly cellulose pulp dissolution that is free of emissions, free of involvement of elevated temperatures, also allowing easy recovery of reagents.

16. A system for dispersion based dissolution of solids including viscosity enhancing polymers and hard-to-wet solids in solvent systems by the process as claimed in claim 1-15 comprising: a high speed mixer (HSM) including a high shear region including a high speed rotating impeller blade means (R) defining said high shear region for mixing; said high shear region of the high speed mixer (HSM) having feed inlet means (FC / FB) for direct operative connect to supply said solvent system (SI) and said plug form solid therein selectively in (i) dispersible solid supply through operative connect to a solid source (SP) for feeding in feeder barrel (FC / FB) towards generating said plug including compacted solid into high shear region of said high speed mixer (HSM) and (ii) a cooperative feed barrel (FC / FB) connect to said high shear region for supply of said plug form including compacted solid directly into said high shear region for the operative impeller blade (R) to scrap the plug form solid in said highshear region for its rapid dispersion and wetting in said solvent systems restricted within said high shear zone of the mixer only under action of said high shear mixing, free of any solid-solvent interaction or feed blockage outside said high shear region in said mixer and avoiding difficult to dissolve agglomeration and / or viscous gel layer formation on the solid thereby facilitating rapid dispersion based dissolution of solids.

17. The system as claimed in claim 16 wherein said feed barrel (FC / FB) is integrated with a powdering mill (M) for powdering the solid, and carrying to cyclone separator (C) in connection for air based extraction in the cyclone (C) fitted internally or externally with an extrusion screw (ES) to collect, compress and advance the powdered solid through the extrusion screw to said barrel and onward feed into said high shear zone of said high shear mixer.

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