Process for handling particulate coal-based feedstocks

Abstract

A process for manufacturing a liquid suspension of a purified coal product (PCP) is provided. The process comprises the steps of providing a solid PCP wetcake, wherein the PCP is comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and a moisture content of at least 20%m; and inducing a phase inversion of the solid PCP wetcake by addition of a minor amount of an emulsifier. Compositions, pumpable liquid suspensions and asphalt emulsions comprising the suspensions are also provided.

Description

[0001] PROCESS FOR HANDLING PARTICULATE COAL-BASED

[0002] FEEDSTOCKS

[0003] CROSS REFERENCE TO RELATED APPLICATION

[0004] This application claims priority to U.S. Provisional Application Serial No. 63 / 606,282, filed December 05, 2023, the entire contents of which are incorporated herein by reference.

[0005] FIELD OF THE INVENTION

[0006] The invention relates to compositions and methods for the preparation of fluid coal-water suspensions having high solids content and uses thereof.

[0007] BACKGROUND OF THE INVENTION

[0008] The use of coal in water liquid slurries as fuels dates back to the mid-20thcentury when researchers began exploring alternative ways to utilize coal for power generation. The primary motivation behind this development was to improve the efficiency of coal combustion and reduce environmental emissions, particularly in the context of coal-fired power plants. In the 1950s and 1960s, various methods were devised to create coal-water slurries, which involved grinding coal into fine particles and mixing it with an amount of carrier water and a range of other additives to form a pumpable fuel. This approach promised better combustion characteristics, lower emissions, and increased fuel flexibility. Over the decades, research and development efforts continued to refine the technology, leading to the commercial use of coal-water slurries in a range power generation and heating applications, with a focus on enhancing energy efficiency and reducing environmental impacts.

[0009] WO-81 / 01152-Al (Alfred University Research Foundation) describes a conventional approach to production of a so-called high solids content coal-water slurry that is suitable for use in the generation of heat energy in a furnace equipped with a cyclone or turbulent type of burner. Such slurries were utilised in commercially operated coal-slurry pipelines for long distance delivery to power plants, at least until the use of coal as a primary source of energy began to decline at the turn of the century as a result of the modern trend to decarbonisation of the fuel economy. Nevertheless, such coal-water slurries were typically characterised the use of large volumes of carrier water added to the pulverised dry coal feedstock. By way of example, WO-81 / 01152-Al explains that a 50%m solids content coal-water slurry requires around 1000 litres of carrier water per tonne of coal (around 250 US gallons per ton); whilst a 75 %m solids content coal- water slurry requires around 300 litres of carrier water per tonne of coal (around 83 US gallons per ton). Evidently, such approaches are highly water intensive and of limited viability in geographies where water is a scarce resource. An additional related problem associated with the use of these coal-water slurries was the generation of wastewater underflows containing left over fines and ultrafines that create a disposal risk to the environment.

[0010] Coal fines and ultrafines, including microfines, are the small particles of coal generated from larger lumps of coal during the mining and preparation process. Coal fines are generally considered a waste product as the particulate nature of the product renders it difficult to market and transport. As much as 70-90 million tonnes of coal fines have been produced in the US alone as waste by-product every year by the mining industry (Baruva, P., Losses in the coal supply chain, IEA Clean Coal Centre Rep. CCC / 212, p.26, December 2012, ISBN 978-92-9029-532-7), the vast majority of which is left unused. Coal fines are therefore generally discarded as spoil close to collieries and coal fired power plants forming large waste heaps or contained in large ponds that require careful future management in order to avoid environmental contamination.

[0011] The shift away from the use of fossil fuels, to mitigate the effects of climate change, has reduced demand for coal as a ready source of thermal energy. However, this has not reduced the global demand for high quality carbon feedstocks for a wide range of specialty end-products. Included amongst these are useful products such as activated carbon, for decontamination of gases and liquids, as well as asphalt emulsions which find use in road surfacing and general paving. Both of these products can be manufactured from petroleum-based feedstock, however it would be desirable to utilise abundant waste materials that can be enriched for their carbon content in order to reduce future reliance on petroleum extraction, thereby hastening the progress towards net-zero targets.

[0012] Hence, it would be advantageous to provide more sustainable sources of carbon, ideally from upcycled waste materials, for use in the manufacture of specialty end-products. In particular, it would be desirable to improve the handling characteristics of such upcycled waste materials so that they can be readily incorporated into existing industrial processes. These and other uses, features and advantages of the invention should be apparent to those skilled in the art from the teachings provided herein.

[0013] SUMMARY OF THE INVENTION

[0014] The invention relates to improvements in processes for converting a solid particulate purified coal product material into an aqueous liquid suspension without the need for addition of significant volumes of carrier water. Surprisingly, the inventors have identified a process of phase inversion that enables release of inherent moisture retained within a solid particulate composition of purified coal so as to form a continuous liquid phase within which the coal particles are suspended. The resultant liquid suspension has a higher density of coal particles per unit volume compared to the solid starting material and can be easily pumped and mixed into other liquid feedstocks, such as asphalt emulsions.

[0015] In a first aspect the invention provides for a process for manufacturing a liquid suspension of a purified coal product (PCP) comprising the steps of:

[0016] - providing a solid PCP wetcake, wherein the PCP is comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and a moisture content of at least 20%m; and

[0017] - inducing a phase inversion of the solid PCP wetcake by addition of a minor amount of an emulsifier.

[0018] In specific embodiments the PCP wetcake has a moisture content of at least 30%m, optionally at least 40%m and suitably at least 50%m.

[0019] In specific embodiments the PCP is comprised of coal particles having a d90 particle size of less than 25 microns.

[0020] In specific embodiments the liquid suspension of PCP exhibits properties of a hydrosol.

[0021] In specific embodiments the emulsifier is added in an amount of less than 30%m, optionally less than 20%m, suitably less than 10%m of the total of the combined mass of the solid PCP wetcake and emulsifier. Typically, the emulsifier is added in an amount of around 5%m of the total of the combined mass of the solid PCP wetcake and emulsifier. Suitably, the emulsifier is added via a low energy mixing step. In specific embodiments the emulsifier comprises an anionic substance, a cationic substance or an amphoteric substance.

[0022] In specific embodiments no additional carrier water is added to form the liquid suspension. Typically, the liquid phase of the liquid suspension is substantially comprised of the moisture content of the solid PCP wetcake. In some cases, up to 10%m additional carrier water may be necessary.

[0023] In specific embodiments the liquid suspension has a dynamic viscosity of not more than 600 cP, suitably not more than 400 cP and optionally around 200 cP.

[0024] In specific embodiments the liquid suspension of PCP has a total water content inclusive of inherent moisture of not more than 50%m.

[0025] In specific embodiments the liquid suspension of PCP is stable and exhibits substantially no settlement for a period of at least 24 hours after manufacture.

[0026] In specific embodiments the solid PCP wetcake comprises a coal selected from: a bituminous coal; a sub-bituminous coal; or lignite.

[0027] A second aspect of the invention provides for a pumpable liquid suspension of PCP obtainable according to a process as described herein.

[0028] A third aspect of the invention provides a liquid suspension of PCP, wherein the PCP is comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and wherein the liquid suspension has a total water content inclusive of inherent moisture of not more than 60%m.

[0029] In specific embodiments the liquid suspension has a dynamic viscosity of not more than 600 cP, suitably not more than 400 cP and optionally around 200 cP or less. Typically, the liquid suspension is the result of a phase inversion of a solid PCP wetcake. Suitably, the liquid suspension further comprises an emulsifier in an amount of less than 30%m, optionally less than 20%m, suitably less than 10%m of the total of the combined mass of the liquid suspension. Optionally, the emulsifier is present in an amount of around 5%m of the total of the combined mass of the liquid suspension. A fourth aspect of the invention provides a method of using a liquid suspension of PCP obtainable according to a process as described herein as an additive in the manufacture of an asphalt emulsion, the method comprising combining the liquid suspension of PCP with a feedstock of the asphalt emulsion or with the asphalt emulsion itself.

[0030] A fifth aspect of the invention provides a method for using a liquid suspension of PCP as an additive in the manufacture of an asphalt emulsion, the method comprising combining the liquid suspension with a feedstock of the asphalt emulsion process or with the asphalt emulsion itself.

[0031] A sixth aspect of the invention provides a process for the manufacture of a PCP-asphalt emulsion, the process comprising combining a PCP additive with a feedstock of the asphalt emulsion or with an asphalt emulsion itself, wherein the PCP additive comprises a liquid suspension of PCP, and wherein the PCP is comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and wherein the liquid suspension has a total water content inclusive of inherent moisture of not more than 50%m and a dynamic viscosity of not more than 600 cP.

[0032] A seventh aspect of the invention provides a composition comprising: a phase inverted liquid suspension of a PCP comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and a moisture content of at least 20%m; and an anionic emulsifier; wherein the composition has a total water content of less than 60%m.

[0033] An eighth aspect of the invention provides a composition comprising: a phase inverted liquid suspension of a PCP comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and a moisture content of at least 20%m; a cationic emulsifier; and hydrochloric acid wherein the composition has a total water content of less than 60%m. Further aspects of the invention provide for asphalt emulsions comprising the compositions described herein and above in an amount of up to 10%m, suitably up to 15%m, typically up to 20%m, optionally up to 30%m.

[0034] Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible.

[0035] BRIEF DESCRIPTION OF THE DRAWINGS

[0036] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0037] Figure 1 is a schematic of a process asphalt emulsion manufacture and routes (A, B and C) by which phase-inverted PCP composition can be added according to embodiments of the present invention.

[0038] Figure 2 shows photographs (a) - (d) that illustrate stages of a process according to one embodiment of the present invention, (a) PCP-A wet cake, grated to ~3 mm particles; (b) following addition of an amphoteric lignin emulsifier the mixture has the consistency of “batter”; (c) further mixing reduces “batter” viscosity and homogenises composition; (d) after around one minute of mixing, a uniform fluid suspension is formed.

[0039] Figure 3 shows photographs (a) - (d) that illustrate stages of a process according to a further embodiment of the present invention, (a) PCP-A wet cake, following lump breaking into large chunks; (b) following addition of an amphoteric lignin emulsifier the mixture has a stiff lumpy consistency; (c) further mixing liberates inherent water within the PCP and further homogenises composition; (d) after around three minutes of mixing, a uniform fluid suspension is formed.

[0040] Figure 4 shows a graph indicating the amount of emulsifier required for a 200 cP fluid suspension of PCP across a range of solids contents (%m). DETAILED DESCRIPTION OF THE INVENTION

[0041] All references cited herein are incorporated by reference in their entirety. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0042] Prior to setting forth the invention in greater detail, a number of definitions are provided that will assist in the understanding of the invention.

[0043] As used herein, the term "comprising" means any of the recited elements are necessarily included and other elements may optionally be included as well. "Consisting essentially of’ means any recited elements are necessarily included, elements that would materially affect the basic and novel characteristics of the listed elements are excluded, and other elements may optionally be included. "Consisting of’ means that all elements other than those listed are excluded. Embodiments defined by each of these terms are within the scope of this invention.

[0044] The term “coal” is used herein to denote readily combustible sedimentary mineral-derived solid hydrocarbonaceous material including, but not limited to, hard coal, such as anthracite; bituminous coal; sub-bituminous coal; and brown coal including lignite (as defined in ISO 11760:2005). “Native” or “feedstock” coal refers coal that has not been subjected to extensive processing and comprises a physical composition (e.g. maceral content) that is substantially unchanged from the point of extraction.

[0045] As used herein, the term “ash” refers to the inorganic - e.g. non-hydrocarbon - mineral component found within most types of carbonaceous materials of geological or natural origin such as coal, graphite ore, char or biochar. Ash that is comprised within the solid residue that remains following combustion of coal is sometimes referred to as fly ash. As the source and type of carbonaceous feedstock is highly variable, so is the composition and chemistry of the ash. However, typical ash content includes several oxides, such as carbonate, silicon dioxide, calcium oxide, iron (III) oxide and aluminium oxide, that may be present in the form of minerals such as feldspar, quartz, chalk and mica. Depending on its source, carbonaceous feedstocks such as coal may further include in trace amounts one or more substances that may be comprised within the subsequent ash, such as arsenic, beryllium, boron, cadmium, chromium, cobalt, lead, manganese, mercury, molybdenum, selenium, strontium, thallium, and vanadium. In the production of high purity PCP liquid suspensions, it is desirable to reduce the ash content of the coal material prior to incorporation into specialty carbon containing products such as asphalt emulsions or activated carbon.

[0046] The term “purified coal product” or “PCP” as used herein refers to a material that is comprised of a carbon-containing, hydrocarbonaceous or carbonaceous, substance of geological or biological origin - e.g. coal. A PCP is typically subjected to various process steps to reduce non- carbonaceous substances that are present, such as ash or sulfur, to a minimum. Purified coal compositions are different to coals in their native or un-purified state. Typically, the PCP of geological origin according to embodiments of the present invention will comprise an ash content of less than 8 wt%, suitably less than 5 wt%, optionally less than 2 wt%, in certain cases less than 1 wt%, and in specific embodiments no more than 0.5 wt%.

[0047] As used herein the term “low ash coal” refers to native coal that has a proportion of ash-forming components that is lower when compared to other industry standard coals. Typically, a low ash native or feedstock coal will comprise less than around 12 wt% ash. The term “deashed coal”, or the related term “demineralised coal”, is used herein to refer to coal that has a reduced proportion of inorganic minerals compared to its natural native state. Ash content may be determined by proximate analysis of a coal composition as described in ASTM D3174 - 12 Standard Test Method for Ash in the Analysis Sample of Coal and Coke from Coal.

[0048] ASTM coal classification system (ASTM D388-23) defines coal types according to fixed carbon on a dry, mineral-matter- free basis (dmmf) and / or moist calorific value. Volatile matter (VM, dmmf) is calculated as 100 - fixed carbon (dmmf) and is more often used in practice to differentiate coals of different rank.

[0049] • Anthracite: 2%m - 8%m VM(dmmf)

[0050] • Semi-anthracite: 8%m - 14%m VM(dmmf)

[0051] • Tow- volatile bituminous coals: 14%m - 22%m VM(dmmf)

[0052] • Medium- volatile bituminous coals: 22%m - 3 l%m VM(dmmf)

[0053] • High volatile bituminous coals, Sub-bituminous coals and Tignites: >31 %m VM(dmmf), but distinguished by their calorific value at their natural bed moisture; i.e. as mined but free from any moisture on the surface of the lumps. As used herein, the term “coal fines” refers to coal in particulate form with a maximum particle size typically less than 1.0mm. The term “coal ultrafines” or “ultrafine coal” or “ultrafines” refers to coal with a maximum particle size typically less than 0.5mm (500 microns (pm), approximately 0.02 inches). The term “coal microfines” or “microfine coal” or “microfines” refers to coal with a maximum particle size typically less than 20 pm.

[0054] Most suitably the particle size of the PCP that is utilized in the presently described processes may be at most 1000pm or 500 pm. Specifically, the maximum average particle size may be at most 500 pm. More suitably, the maximum average particle size may be at most 300 pm, 250pm, 200pm, 150pm, or 100pm. Most suitably, the maximum average particle size may be at most 75pm, 50pm, 40pm, 30pm, 20pm, 10pm, or 5pm. The minimum average particle size may be 0.001 pm, 0.01pm, 0.1pm, 0.5pm, 1pm, 2pm, or 5pm. Hence, in particular embodiments the invention includes utilisation of nanoscale fines with average particle sizes in the sub-micron range.

[0055] An alternative measure of particle size is to quote a maximum particle size and a percentage value or “d” value for the proportion by volume of particles within the sample or composition that fall below that particle size. For the present invention, any particle size of PCP that is suitable for use as a feedstock or as a component of a PCP wetcake composition is considered to be encompassed by the invention. Suitably, the particle size of the PCP is in the ultrafine range. Most suitably the particle size of the PCP is in the microfine range. Specifically, the maximum particle size may be at most 500 pm. More suitably, the maximum particle size may be at most 300 pm, 250 pm, 200 pm, 150 pm, or 100 pm. Most suitably, the maximum particle size may be at most 75 pm, 50 pm, 40 pm, 30 pm, 25 pm, 20 pm, 15 pm, 10 pm, or 5 pm. The minimum particle size may be 0.01 pm, 0.1 pm, 0.5 pm, 1 pm, 2 pm, or 5 pm. Any “d” value may be associated with any one of these particle sizes. Suitably, the “d” value associated with any of the above maximum particle sizes may be d99, d98, d95, d90, d80, d70, d60, or d50. A d value may also, or additionally, represent a mass division diameter; the diameter which, when all particles in a sample or composition are arranged in order of ascending mass, thereby dividing the mass into specified percentages. The percentage mass of a composition below the diameter of interest is the number expressed after the "d". Hence, a d90 of 10 pm can indicate that 90 percent of the mass of the composition is comprised within particles of less than 10 pm in diameter. To optimise the process of phase inversion of solid PCP wetcake into a relatively stable liquid suspension it is desirable for the particle size to be both relatively homogeneous and small. For instance, in a specific embodiment of the invention the PCP has a d90 or higher of <100 pm, <90 pm, <70 pm, <50 pm, <25 pm, optionally <20 pm, suitably <10 pm. In some embodiments of the invention, the PCP has a d99 of <70 pm, <60 pm, <50 pm, <40 pm, <25 pm, optionally <20 pm, suitably <10 pm.

[0056] Particle size can be characterized by a number of different techniques (laser diffraction, dynamic light scattering, electrophoretic light scattering, automated imaging, sedimentation, etc.) which do not always correspond exactly. In a specific embodiment of the invention, laser diffraction techniques are employed to measure particle size distributions and to specify particle size parameters.

[0057] In embodiments of the present invention the particles of the PCP may have a planar, flattened or plate / disc-like morphology. Planar morphologies are typically derived from bituminous coal feedstocks and in such embodiments, the reference to a maximum or average particle size as mentioned above refers to the maximum diameter of the particle, that is the diameter of the planar surface of the PCP particle.

[0058] As used herein, the term “water content” refers to the total amount of water within a sample of PCP and is expressed as a concentration or as a mass or weight percentage (m% or wt%). As PCP is obtained from coal, a geologically derived natural mineral material, it includes a level of entrained moisture, as well as any moisture that has been absorbed from the environment. The moisture content of coal includes contributions from fractions that are defined as surface, inherent and residual moisture. Water adhering to the outside of a coal particle is referred to as surface or adventitious moisture (defined in ASTM method D388). Water that occurs in the microscopic structure of the coal, generally filling pores, but not visible in large fractures is called inherent moisture (defined in ASTM methods D388 and D1412). Water remaining in coal after air-drying a sample and minor heating in a moisture oven to 104 to 110°C is referred to as residual moisture (defined in ASTM method D121). The combination of these fractions typically forms the value given to the moisture content of a given coal when undertaking a proximate analysis. The capacity to retain considerable amounts of moisture is increased when coal is in particulate form, particularly in the form of a PCP that has been obtained from waste microfines comprised within underflow and that has been refined via froth flotation techniques. Even following dewatering techniques, such as filter pressing, a PCP wetcake may present as apparently dry to the touch and as a solid for the purposes of handling / shipping, but still contain moisture content of at least 25 %m, at least 30%m, at least 40%m, at least 50%m and up to 60%m. Slurrification is the combination and mixing of a solid substance with a liquid to form a slurry, where the solids are suspended in the liquid. Here, the solid is PCP and the liquid is water. A slurry is a mixture of denser solids suspended in liquid, usually water. The most common use of slurry is as a means of transporting solids or separating minerals, the liquid being a carrier that is pumped. A coal-water slurry mixture is a complex solid-liquid dispersion and typically contains:

[0059] • 50-75%m of coal (inclusive of inherent moisture), with a maximum particle size of approximately 300 pm,

[0060] • 25-50%m of carrier water,

[0061] • 1% of additives, such as dispersants or surfactants.

[0062] Because of the average particle size in typical coal-water slurry is much larger (approximately one order of magnitude) than the particle size of PCP, the average surface area per particle in a coalwater slurry is much lower, and significantly less water is adsorbed on the surface of the coalwater slurry particles. This results in a coal-water slurry exhibiting liquid properties for water contents at which PCP is a “touch-dry” solid.

[0063] As used herein, the term “colloid” is defined as a mixture in which one substance comprising microscopically dispersed insoluble particles, typically in the nanoscale, are suspended throughout a continuous phase of another substance. The term “suspension” is distinguished from colloids by larger particle size, e.g. including particles in the microscale. A “sol” is a colloidal suspension with solid particles (typically <1 micron diameter) in a liquid, e.g. blood, pigmented ink, cell fluids, paint, antacids and mud. If the dispersion medium is water, the colloid may be called a hydrosol. A hydrosol cannot readily be fdtered or centrifuged to remove water unlike a suspension.

[0064] Phase inversion is the process of interconversion between types of colloids or emulsions, e.g. water-in-oil to oil-in-water emulsions, or of a solid-in-liquid colloid to liquid-in solid. Phase inversion can be induced by shifting emulsifier affinity from one phase to the other. Phase inversion of solid-in-liquid to liquid-in-solid is widely used in the fabrication of polymers, cosmetic products, pharmaceutical products, foodstuff and detergents. Examples of phase inversion from liquid-in-solid to solid-in-liquid are rare. As used herein the term “dewatered coal” refers to coal that has an absolute proportion of water that is lower than that of its natural state. The term “dewatered coal” may also be used to refer to coal that has a low, naturally occurring proportion of water. Water content may be determined by analysis of a native or purified coal composition as described in ASTM D3302 / D3302M - 17 Standard Test Method for Total Moisture in Coal. Water content may also apply to the inherent level of moisture present in products comprised of PCP, such as pellets or granules that comprise PCP as a minority or majority constituent.

[0065] Demineralising and dewatering of carbonaceous feedstocks, such as coal fines, most suitably from waste or discard sources, to produce a PCP may be achieved via a combination of froth flotation separation, specifically designed for ultrafines and microfine particles, plus mechanical and thermal dewatering techniques. Typically, PCP may be produced from a particulate carbon- containing feedstock, such as waste bituminous or sub-bituminous coal fines, via processes that comprise particle size reduction, mineral matter removal, dewatering and drying. Some or all of these steps may be altered or modified to suit the specification of the starting material or of the desired end product. The key process steps are summarised below in relation to a typical starting material derived from an impoundment, tailings pond or production tailings underflow. It should be noted that the inventors have found that in order to achieve high-purity specialty end products it is desirable to reduce ash content in the PCP feedstock to levels <3 m%, optionally <2m% more suitably < 1 m% which is achievable at economic scale via the processes described herein.

[0066] Particle size reduction

[0067] The starting carbonaceous material feedstock is reduced to a particle size of d80=30-50 microns (or finer in some coals) to achieve efficient separation to a target mineral matter (ash) content of 7-10 wt%. To achieve this, a feed comprising the starting material is diluted with water to achieve a solids content of in the range 20-40 wt%, then ground in a ball or bead mill depending on the top size of the feedstock. The product is screened or processed in a hydro-cyclone at a nominal size range of approximately 100 microns to exclude particles above this size. Suitable equipment for size reduction is manufactured by Metso Corporation, Fabianinkatu 9 A, PO Box 1220, FI- 00130 Helsinki, FIN-00101, Finland; Glencore Technology Pty. Ftd., Fevel 10, 160 Ann St, Brisbane QFD 4000, Australia, and FFSmidth, Vigerslev Alle 77, 2500 Valby, Denmark. Ash removal

[0068] One or a series of froth flotation stages are carried out to bring the entrained mineral content down to the target level. For some coals where the mineral matter is disseminated mainly within sub- 10-micron size domains, more than one stage of flotation following further milling may be required to achieve a low ash level.

[0069] During froth flotation a coal slurry is diluted further with water typically to a range of 2-20 wt% solids then collected in a tank and froth flotation agents, known as frother (e.g. methyl iso-butyl carbinol dipropyleneglycol monomethyl ether, dipropyleneglycol monomethyl ether or pine oil) and collector (e.g. biodiesel, diesel fuel, kerosene, cyclohexane, or other hydrocarbon oil, biodiesel or other fatty acid methyl ester, or flotation reagent Nalco 8836 plus from Ecolab, Naperville, IL, USA), are added using controlled dose rates. Micro particle separators (e.g. Flotation test machines manufactured by Eriez Manufacturing Co., 2200 Asbury Road, Erie, Pa. 16505, USA, by FLSmidth, Vigerslev Alle 77, 2500 Valby, Denmark, by Metso Corporation, Fabianinkatu 9 A, PO Box 1220, FI-00130 Helsinki, Finland, and GTEK Mineral Technologies Co. Ltd.) fdled with process water and fdtered air from an enclosed air compressor are used to sort hydrophobic carbon materials from hydrophilic mineral materials. Froth containing hydro- carbonaceous particles overflows the tank and this froth is collected in an open, top gutter. The mineral pulp is retained in the separation tank until discharged, whereas the demineralised coal slurry is de-aerated, before being subjected to additional processing. After each flotation stage a series of cyclones are used to selectively remove excess water and any oversized particles prior to the next stage of milling. After the final milling stage, decanter centrifuges are incorporated into the process design to remove particles above 10 microns in size and to further reduce water content. Suitable equipment is manufactured by Alfa Laval Corporate AB, Rudeboksvagen 1, SE- 226 55 Lund, Sweden.

[0070] Dewatering

[0071] The concentrate from froth flotation is dewatered with a filter-press or tube-press to a target range of 20-50wt% depending on the actual particle size, under pressure or vacuum, sometimes with airblowing, to remove water by mechanical means, in order to generate feed for the extruder. Suitable fdter-press equipment is manufactured by Metso, FI-00130 Helsinki, Finland, FLSmidth, Valby, Denmark, and by Outotec. Rauhalanpuisto 9, 02230 Espoo, Finland. The resultant solid material is referred to as PCP wetcake.

[0072] In some instances, flocculant (or thickener, e.g. anionic and cationic polyacrylamide additives manufactured by Nalco Champion, 1 Ecolab Place, St. Paul, MN 55102-2233, USA) is added to optimise both settling properties of PCP and inorganic waste and underflow density. To optimise the procedure settling tests are carried out to measure settling rates and generate a settling curve, tracking underflow density with time. Filtration may also be necessary depending on the fdtration rate and resultant cake moisture. To optimise the procedure feed % solids (thickened / unthickened), feed viscosity, pH and fdtration pressure will be measured, Filter cloths are chosen after assessment of cake discharge and blinding performance. Suitable fdter cloths are manufactured by Clear Edge Filtration, 11607 E 43rd Street North, Tulsa, Oklahoma 74116 USA.

[0073] In specific embodiments, PCP derived from coal is characterised has having particles that adopt a flattened disc or plate-shaped morphology. This unique morphology is distinct from conventional particles of virgin coal which tend to be more irregular agglomerates having a substantially globular morphology. Without wishing to be bound by theory, it is believed that improved dispersion characteristics in liquid emulsions and suspensions may be associated with such flattened disc or plate-shaped morphology.

[0074] PCP wetcake

[0075] The term ‘wetcake’ may be slightly equivocal as the product appears as a touch-dry, lumpy solid. Consequently, PCP wetcake can be considered as difficult to handle especially where it is desired as a feedstock for various liquid based processes. PCP wetcake typically contains around 40 to 60%m moisture (i.e water) held within a solid organic coal matrix which is classified as surface, inherent and / or residual moisture by proximate analysis. The coal matrix contains particles ranging in diameter from 100 nm to 20 microns (typically loosely bound together to form lumps), so it is for all intents and purposes a solid material in which moisture (i.e. water) is held by capillary forces. As mentioned, typically the individual particles have a flattened plate-like structure which improves cohesiveness and facilitates moisture retention.

[0076] Although the fundamental understanding of water retention behaviour in carbonaceous coal is still limited (Eiu A., Eiu S., Eiu P. & Wang K., (2021) Water sorption on coal: effects of oxygen- containing function groups and pore structure. Int J Coal Sci Technol 8, 983-1002) weak carbon- water dispersive attractions and strong water-water associative interactions are considered to be controlling factors. Primary water adsorption occurs via hydrogen bond formation at hydrophilic sites with polar oxygen-containing groups on the coal molecular surface. This is followed by the secondary multilayer adsorption and capillary condensation that results in the formation of water clusters held together by water bridges and pore filling. These capillary bridges can also contain smaller particles that can form solid bridges between the larger particles (Yang T., Sega M. & Harting J., Capillary-bridge forces between solid particles: Insights from lattice Boltzmann simulations, AIChE Journal 2021;67:el7350). Both the liquid and solid bridges contribute to the cohesive nature of the coal particles in PCP wetcake and can make the coal particles of the PCP difficult to disperse into another liquid such as a carrier water.

[0077] The inventors have found that adding a surfactant, such as an anionic or cationic emulsifier, to the wet cake reduces the surface tension of the retained moisture, minimizing the attractive forces in the capillary bridges. Furthermore, the polar end of the surfactant can interact with the water, while the non-polar end can interact with the organic moieties on the coal surface. Without wishing to be bound by theory, this “liberates” the film of water from the surface of the coal particle, allowing the coal particles to move more freely through the resultant fluid.

[0078] There are clear technical and commercial advantages arising from the presently described processes that relate to inverting solid PCP wetcake containing moisture into a fluid which contains the PCP particles. A fluid form of PCP improves ease of transport, storage and mixing with other components. For example, in asphalt emulsion manufacturing combination of compatible and miscible liquids is both cheaper and less CO2 emission intensive. Furthermore, it has been found that the density of PCP is significantly increased in the fluid form (in the range 1124 - 1135 kg / m3) compared with solid wetcake (approximately 600-650 kg / m3).

[0079] In embodiments of the invention a fluid in the form of a liquid suspension is prepared from a solid PCP wetcake as a phase inverted fluid that readily flows under gravity. The phase inverted liquid PCP is described herein as a suspension because most PCP particles are larger than those typically found in a colloid (i.e. >1 micron diameter). However, surprisingly the phase inverted liquid PCP possesses filtration and centrifugation properties that are similar to a hydrosol. Nevertheless, since some particles within the fluid composition can begin to separate under gravity after an extended period, the liquid PCP has some similarities to a suspension as well. However, it is apparent that the present liquid suspensions are fundamentally different in terms of particle size and overall water content (i.e. moisture plus carrier water) to conventional coal-water slurries.

[0080] Accordingly, in embodiments the compositions of the invention comprise a phase inverted liquid suspension of a PCP that may further comprise an emulsifying agent. The emulsifying agent may be an anionic emulsifier, amphoteric or a cationic emulsifier (see further discussion below).

[0081] Having the ability to utilise PCP wetcake in a homogeneous fluid form has advantages for manufacturing emulsions using PCP as a component. Mixing components in a colloid mill is central process step in asphalt emulsion production, for example, and a colloid mill typically accepts two liquid feeds, liquid asphalt and an aqueous stream. Introducing a PCP in fluid form requires little or no process modifications, whereas adding PCP as solid wetcake is inevitably more complicated to engineer, requiring various mixing and homogenisation steps. Furthermore, any potential disruption in colloid mill operations from the presence of solid particle aggregates could affect the rate of production adversely. A fluid form of PCP wetcake has the added benefit of being miscible with commercial asphalt emulsions and may be utilised as a component to blend with emulsions after the colloid mill stage of production.

[0082] Asphalt emulsions are suspensions of micron-sized asphalt globules in water. Hot liquid asphalt is sheared into small droplets in a colloid mill in the presence of water and an emulsifier, which delays the asphalt droplets from coalescing, forming larger agglomerates and settling out.

[0083] Two main types of emulsifiers are typically employed: anionic or cationic. The choice of emulsifier is often dictated by availability and by potential interaction with the substrate. Anionic emulsions have a high pH and are compatible with limestone aggregate. Cationic emulsions have a low pH and are not compatible with limestone aggregate but work well with granite aggregate. In compositions of the present invention cationic emulsifiers are typically combined with hydrochloric acid.

[0084] Asphalt emulsions form stable structures with the asphalt molecules (oil phase) being stabilized within the continuous phase (water) through means of emulsifiers acting as a bridge bringing together the oil and water into close proximity. When introducing a PCP wetcake to the emulsion, favourable non-covalent interactions take place between the PCP particles and the asphalt particles (which are of similar size) resulting in a stable structure complimenting the original emulsion design. Without wishing to be bound by theory, two potential scenarios are hypothesized regarding the precise interactions:

[0085] • aggregates of PCP particles are encapsulated by the asphalt droplet shielding the wetcake from the aqueous phase, and / or

[0086] • the PCP particles self-attach to the surfaces of the asphalt droplets.

[0087] According to embodiments of the present invention, a novel transformation from solid PCP wetcake to a fluid form has been achieved: a phase inverted fluid that has been prepared by low energy mixing with emulsifiers (anionic, cationic and amphoteric) at the appropriate pH. Advantageously, the conversion from solid to liquid is achieved without the addition of substantial volumes of carrier water as would be required in conventional slurrification processes.

[0088] An asphalt emulsion process line up, according to an embodiment of the invention, is shown in Figure 1. A colloid mill operates at 70°C - 95°C to which liquid asphalt (pre-heated at 120°C - 160 °C) is mixed with an aqueous stream. The aqueous stream is a mix of emulsifier, stabilizer and acid (or alkali) with water prepared at 20°C - 60°C to which optionally latex has been added in-line.

[0089] A phase-inverted liquid suspension of PCP wetcake can be blended to produce a PCP-asphalt emulsion in three different routes, see Figure 1 :

[0090] A. By addition to a conventional, commercial asphalt emulsion in a separate mixing tank,

[0091] B. By addition into the colloid mill via an extra feed to mix with the asphalt and aqueous streams,

[0092] C. By addition into the aqueous mixing tank as an extra feed or together with the one of the other streams.

[0093] Asphalt emulsions vary widely in composition, specification and use. Various recipes are used for different applications, and each may comprise a proportion of phase inverted liquid suspension of PCP as an additive:

[0094] Tack coat is applied to a clean, prepared pavement surface using the spray bar of a tack truck. Once the emulsion breaks from water evaporation, the next pavement layer is constructed on top of the tack coat, thus, avoiding slippage. • No track tack coats were developed to reduce the amount of tack pulled up by the tires of the construction equipment while placing the next lift. These are usually designed with a harder penetration asphalt and to break quickly.

[0095] • Prime coat is applied to a prepared base to protect its integrity before the addition of pavement lifts, and to reduce dust. It is frequently diluted with water prior to application. Specific to prime coat is the addition of oil, usually naphtha to allow better coating and penetration of the base.

[0096] • Fog seal is applied to an aging or fading existing pavement or a new chip seal. Wear and tear allow the aggregate to be more visible, and use can make pavements look white or gray.

[0097] • Chip seals extend pavement life by giving protection from oxidation and water intrusion, hence treating friction loss cracking. The emulsion is applied first, followed by a layer of a specific size of clean, dry aggregate chips, then embedded with a roller. Aggregate chip retention is critical.

[0098] • Microsurfacing corrects minor surface profile irregularities, fills ruts, protects against moisture damage, UV and wear. It requires a polymer modified emulsion, plus aggregate, hydrated lime or Portland cement, and water. A compatible tack coat is applied before microsurfacing.

[0099] • Slurry seal waterproofs and seals the pavement surface with a mix of asphalt emulsion, fine aggregate, mineral filler, water and lime or Portland cement. It can fill minor cracks, increase skid resistance and improve the aesthetics.

[0100] • Cape seal is a chip seal followed by a slurry seal.

[0101] • Scrub seal resembles a chip seal, but targets surface imperfections with smaller aggregate. An emulsion is applied and worked into surface cracks. A chip spreader follows applying the fine aggregate which is broomed into the cracks and voids. Fast is the roller to help adhere the chips.

[0102] Having the ability to utilise PCP wetcake in a homogeneous fluid form has advantages for manufacturing other products containing PCP, such as activated carbon or cementitious materials. For example, activated carbon manufacturing processes, where additives, such as lignite, calcium compounds (oxide, carbonate, nitrate), magnesium compounds, etc. are required, will mix with PCP more readily and more homogeneously in a fluid form. Manufacturing of carbon-rich products, such as activated carbon, is typically from a hydrocarbon feed source such as a PCP, coal and / or biomass using the steps of pyrolysis (heating in a nonoxidizing environment) followed by further activation, such as reaction with steam or carbon dioxide at high temperature to increase porosity or surface area. For instance, conventionally activated carbon with a surface area of 400 m2 / g or greater can be produced from a lignite coal or biochar via the steps of pyrolysis at 450 to 650° C and then reacting with steam or carbon dioxide at temperatures between 750 and 1000° C. Incorporation of a phase inverted liquid PCP into this process is relatively straightforward. By way of example, the PCP in liquid form may be blended with other carbonaceous feedstock materials at the outset. The various process steps can be performed separately, for example, in separate rotary kilns. They can also be performed in a single reactor such as a multiple hearth furnace.

[0103] The invention is further illustrated by the following non-limiting examples.

[0104] EXAMPLES

[0105] Materials

[0106] Two PCP wetcakes, 3 commercial asphalt emulsions and 1 laboratory prepared asphalt emulsion have been used in these examples:

[0107] • PCP -A with moisture content = 48-50 %m, ash content = 1 %m (dry basis), d50 = 3 microns and d99 = 10 microns,

[0108] • PCP-B with moisture content = 42-45 %m, ash content 2.9 %m (dry basis), d50 = 6 microns and d90 = 15 microns.

[0109] Table 1 lists the properties of the four emulsifiers used.

[0110] Table 1. Properties of emulsifiers used in the following examples.

[0111] A B C D

[0112] Chemical type Tignin Fatty acid Tignin Tignin

[0113] Emulsifier type Amphoteric Cationic Anionic Amphoteric

[0114] Setting type Slow-set Quick-set Slow-set Slow-set Main Seal coat Seal coat

[0115] Slurry seal Tack coat applications Tack coat Tack coat

[0116] Four different asphalt emulsions were combined with liquid PCP:

[0117] • Commercial asphalt emulsion A is Anionic No Track Tack (NTT), classified as slow set, low viscosity, hard asphalt, modified with added polymer, obtained from a US Gulf Coast refinery,

[0118] • Commercial asphalt emulsion B is Cationic Slow Set (CSS) formulated for a long working time, obtained from Russell Standard, PA, USA,

[0119] • Commercial asphalt emulsion C is a Cationic Microsurface Emulsion (MSE) and quickset, containing polymer (Styrene butadiene stearate latex), designed to break quickly, also obtained from a US Gulf Coast refinery,

[0120] • Laboratory prepared asphalt emulsion D using a hard US Gulf coast asphalt.

[0121] A “hard” asphalt from a US Gulf Coast refinery with a penetration index of 63 (asphalt I) has also been used. This is performance grade 67 / 22 in the US Superpave grading system based on climate and is suitable for mid-latitude US states.

[0122] Example 1: Slurrification of PCP wetcake (conventional approach)

[0123] To convert PCP wetcake into a pumpable slurry (a solid in liquid suspension), one can simply add carrier water to the solid. By reducing the solids content from ~ 55% to ~ 35% one can create a pumpable slurry with a viscosity of about 200 cP at ambient temperatures. The additional water required for slurrification by water alone is significant: 68 grammes of water per 100 grammes of wet cake is required to achieve a pumpable slurry from wetcake already containing 43 %m water. Such a slurry will only contain 34%m solids and its transportation to an end-user will become uneconomic, thus its suitability for blending into an industrial process is much diminished. Further, since typical asphalt emulsions contain 50% or more solids (asphalt) by weight, adding a stream at only 35% solids would introduce excessive water into the blend. Example 2: Use of anionic emulsifiers to induce phase inversion of a PCP wetcake from a solid to a liquid

[0124] A PCP -A composition is discharged from the filter press of the PCP process in the form of large cakes - up to around 8 cm (~3 inches) thick and around 45 cm (~18 inches) across. These are reduced in size by a lump breaker, and then grated around 3 mm to form a crumb composition using a rotating disk grater, allowing easier handling and mixing of ingredients, see Figure 2(a). The grated wet cake crumb was then combined in a bench top stand mixer (KitchenAid) with a lignin-based amphoteric emulsifier A (available from chemical suppliers such as Ingevity, North Charleston, SC, USA, Arkema, King of Prussia, PA, USA, and Nouron (AkzoNobel Chemicals bv), Amsterdam, Netherlands) and water (pH 11, anionic state), initially having the consistency of “batter”, Figure 2(b). The composition of this mixture is 96 %m PCP-A wetcake and 4 %m emulsifier A. PCP-A wetcake contains 45 %m water (as inherent moisture) and emulsifier A contains 60%m water, so the water content of the resultant mixture is 45.6%m. Hence, the small amount of added water present in the emulsifier is insufficient to convert the wetcake into a slurry simply by suspension alone. With more mixing at 80-110 r.p.m. (i.e. low energy) settings, the emulsifier interacts with the water bridges between the PCP particles, reducing surface tension and viscosity, Figure 2(c). After approximately three minutes of mixing, the solid wet cake crumb has been transformed into a uniform, pumpable liquid suspension of PCP with a viscosity of -200 cP, Figure 2(d), through a process of phase inversion where the coal particles are now suspended in the inherent moisture released as a continuous solvent water phase.

[0125] For larger scale mixing the following mixers are suitable: a pug mill (single or dual shaft) for batch mixing (e.g. as manufactured by Munson Machinery Co. Inc., Utica, NY, USA or S. Howes, Silver Creek, NY, USA) or a ribbon blender (with a single or double helix) for continuous blending (e.g. as manufactured by Munson Machinery Co. or S. Howes).

[0126] With a slightly longer mixing time of approximately 1-2 minutes and using a slightly higher mixer speed of 110 r.p.m., it is possible to avoid the need for finely dividing the PCP starting material, allowing processing of larger chunks of PCP-A wet cake, limited only by the diameter of the mixer blades. In this sequence, the wet cake top size after lump breaking was about 8 cm (-3 inches), see Figure 3(a). After addition of 5%m emulsifier A, early mixing generates a thick, lumpy batter, Figure 3(b), which after some more mixing, Figure 3(c), forms a smooth emulsified liquid suspension of PCP in water, Figure 3(d). The composition of this mixture is 95 %m PCP-A wetcake and 5 %m emulsifier A with a water content of the resultant mixture of 45.75 %m.

[0127] The liquid suspension of PCP thus formed is relatively stable with a high pH (i.e. pH 11-12). Although there may be some minor settling after 7 - 10 days, the sediment is easily stirred back into suspension. Stability was determined using ASTM D244 - Sections 77 to 83, which observes the differences in %m of solids at the top and bottom of a sample after 24 hours, or multiple days of storage.

[0128] No carrier water was added during these tests. The only water in the mixture was from the inherent moisture present originally in the wet cake, and the very small amount of water present as solvent for the added emulsifier composition. Hence, the water in the liquid PCP suspension has been surprisingly “liberated” from the surface of the coal particles, thus making the solid particles mobile within a continuous liquid phase.

[0129] Emulsifier B is fatty acid-derived has a high pH and is useful in anionic systems. Emulsifier B can be used to make a pumpable liquid suspension from PCP-B wet cake using the above-described procedure. The emulsifier dosage for inducing the phase inversion is higher (12%m on a wet basis) than that for emulsifier A.

[0130] Emulsifier C, a slow set lignin type anionic emulsifier, was also used successfully to prepare a liquid suspension from a PCP wetcake.

[0131] Mechanical removal of some of the water from the liquid suspensions derived using emulsifiers A, B and C was attempted by both gravity and pressure filtration. Despite the apparent fluidity of the suspension, minimal liquid water was expressed. Without wishing to be bound by theory, this may imply some type of force equilibrium exists between the aqueous film and the surface of the fine coal particles comprised in the PCP, similar to colloidal behavior (solid in liquid sol). Hence, despite the disruption of the water-coal surface bond, emulsifier addition does not appear to facilitate further removal of water from the wet cake by simple mechanical techniques.

[0132] Example 3: Use of further additives to induce phase inversion of a PCP wetcake from a solid to a liquid

[0133] CMC (Carboxy Methyl Cellulose) is an anionic thickener, but CMC can also be used to stabilize emulsions and has some emulsifying properties. CMC also impacts the ability of a water film to adhere to the surface of the coal particles in a wet cake blend. The addition of l%m CMC on PCP-B wet cake creates a viscous batter when mixed at low speed. Increasing the water content from 45%m to 48%m results in a smooth pumpable liquid suspension. Similarly mixing 5%m hydrolyzed starch paste plus 5%m additional water with PCP-B wetcake results in phase inversion to provide a smooth pumpable liquid suspension of PCP.

[0134] Calcium lignosulfonate can be used as an emulsifier to stabilize oil-water emulsions by reducing the interfacial tension between the two phases. It was found that addition of 5%m calcium lignosulfonate in solid form followed by mixing at 80 r.p.m. with PCP-B wetcake results in the formation of a smooth pumpable liquid suspension of PCP.

[0135] Samples of liquid suspensions derived from emulsifiers A and C (Example 2), calcium lignosulphonate and hydrolyzed starch from PCP-B wetcake were centrifuged at 3,000 r.p.m. for 5 min in a IEC Model HN-S-II laboratory centrifuge. No phase break was observed. This indicates that the blend is stable, showing that the PCP particles do not readily separate into two phases after centrifugation, as would be expected from a particle suspension, thus the phase inverted liquid suspension of PCP is behaving like a colloidal sol.

[0136] Example 4: Impact of emulsifier concentration on PCP wetcake phase inversion

[0137] PCP-B wetcake (58 %m solids) was grated to -3 mm crumb as described in Example 2 and then combined with increasing concentrations of emulsifier A up to 8.2 %m and decreasing amounts of water sufficient to prepare a liquid suspension of PCP with a viscosity of about 200 cP. Figure 4 shows the solids content (% m) required for emulsifier A concentrations between 0 %m and 9 %m; the final water content of each blend is given by (100 - solids content) %m.

[0138] In the absence of emulsifier, PCP-B wetcake has to be diluted by addition of 66 g of water per 100 g of wetcake from 58 %m solids to reach a viscosity of -200 cP at a concentration of 35 %m solids. Figure 4 shows that, after initial addition of 2 %m emulsifier A, the quantity of solids needed to achieve 200 cP increases up to 48 %m solids (just 21 g water added per 100 g wetcake). For with 4 %m emulsifier A the amount of solids increases further to 54 %m. At higher concentrations of emulsifier A the solids content for 200 CP remains relatively constant between 54 %m and 55 %m solids. It was not necessary to add additional water after 4%m emulsifier or at higher emulsifier concentrations. Hence, these results show that for emulsifier concentrations greater than around 3%m the liquid phase requirement for the PCP suspension having a viscosity of -200 cP may be satisfied almost entirely by the inherent moisture content of the PCP wetcake, thereby allowing for phase inversion to occur. Below these concentrations of emulsifier additional carrier water must be added to the wetcake in order to meet the viscosity of -200 cP, thereby also reducing the solids content of the resultant liquid suspension.

[0139] Example 5: Induction of PCP phase inversion by use of cationic emulsifiers

[0140] When a blend of 20%m hydrochloric acid (35% HC1) is mixed with the amphoteric emulsifier A, the pH is lowered from 11 to approximately 2, and the emulsifier becomes cationic. Such a blend also facilitates inversion of the phases of a PCP -A wetcake in a manner identical to that described in Example 2 for an “as received” emulsifier A under anionic conditions. About 4-5 %m of the emulsifier A / HC1 blend is required to achieve a pumpable PCP liquid suspension.

[0141] The fatty-acid derived emulsifier B can be converted to the cationic form but requires more hydrochloric acid to reach pH 2, i.e. 1.25 times as much 35%m hydrochloric acid as emulsifier. Such a blend also facilitates inversion of the phases of a PCP -A wetcake in a manner identical to that described resulting in a pumpable PCP liquid suspension.

[0142] A PCP liquid suspension wetcake derived from emulsifier C in cationic form was spun at 3,000 r.p.m. for 5 min in a IEC Model HN-S-II laboratory centrifuge. No phase break was observed. This shows that the PCP particles do not readily separate into two phases and the phase invenrted liquid suspension of PCP is behaving like a colloidal sol.

[0143] Example 6: Phase inversion of partially-dried, PCP wetcake with amphoteric emulsifier D

[0144] PCP-B wetcake, which had partially dried to approximately 30 %m inherent moisture content, was lightly milled to reduce particle aggregate size. Water was then added to adjust the moisture content of the wetcake to 45 %m and allowed to equilibrate. The wetcake was then mixed with amphoteric emulsifier D under both anionic conditions (no pH change) and under cationic conditions and 0.8 %m of hydrochloric acid (37%) added sufficient to reduce pH to 2). The mixtures were then stirred as described in previous Examples until phase inversion was completed. The resultant liquid suspension was stored in a 100 cm sample tube and observed over time. Static stability was measured over regular time intervals at ambient temperatures using a rod penetration test and the assessed as non-settling, soft settling (1-3 mm of settlement detected), medium settling (3-7 mm of settlement) and hard settling (>7 mm of settlement).

[0145] In the cationic form, non-settling was detected after 7 days storage, but after 12 days hard settling was observed. The anionic form showed non settling after 2 days storage, with first signs of settlement (soft settling) after 3 days storage, followed by medium settling after 5 days and hard settlement after 12 days.

[0146] This example shows that partial removal of water through drying, followed by its replacement, does not affect phase inversion. The process is reversable over this moisture content range.

[0147] Example 7: A liquid suspension of PCP wetcake may be blended with a commercial asphalt anionic emulsion to form a stable PCP asphalt emulsion

[0148] One way of replacing a portion of the asphalt in asphalt emulsions with ultra-fine particles from PCP-B wet cake (route A in Figure 1) is to mix a liquid suspension of PCP with a commercial finished asphalt emulsion. The inherent moisture present in the PCP wetcake contributes to a continuous aqueous phase in the emulsified blend, thus eliminating the need to dry the wet cake prior to blending with the asphalt emulsion.

[0149] A commercial trackless tack emulsion A was mixed with varying quantities of a liquid suspension of PCP-B prepared as described in Example 2. The resultant asphalt emulsion A contained 53 wt% solids and had a viscosity of 120 cP at room temperature. The asphalt emulsion A and the liquid suspension of PCP-B was readily mixed with low intensity stirring. The amount of PCP in the liquid suspension was adjusted to give final blends in which 10%m, 20%m and 30%m of the asphalt was replaced by PCP (calculated on a dry basis).

[0150] All three blends had a viscosity of about 102 cP, slightly lower than that of the original asphalt emulsion. After 8 days in storage at ambient temperatures, the blends appeared stable. A very minor amount of sediment was observed in the 30 % PCP sample which was readily blended back into the bulk with hand stirring. Additional samples were prepared with 50% and 75% of the asphalt replaced by PCP. These blends are still of relatively low viscosity (approximately 150 cP) allowing for ease of handling and application and also appeared to be stable. A very minor amount of sediment was observed in the 30 % PCP sample which was readily blended back into the bulk with hand stirring.

[0151] Stability of the coal / asphalt emulsion can be improved by the addition of approximately 0.5 %m - 1.5 %m of a hydrolyzed starch gel viscosity modifier (e.g. as manufactured by Ingevity, North

[0152] Charleston, SC, USA).

[0153] Example 8: Liquid suspension of PCP wetcake blended with a commercial asphalt cationic emulsions B and C

[0154] Commercial cationic emulsions B and C were mixed with liquid suspension of PCP-B wetcake (10 %m in B, 10 %m and 20%m in C, calculated on a dry basis) according to the approach described in Examples 2 and 5using 4%m of emulsifier A. Sufficient 35% hydrochloric acid solution was added to lower the pH to 2 to avoid any risk of breaking the low pH cationic asphalt emulsions. Both cationic emulsions readily mixed with the liquid suspension of PCP wetcake under low intensity stirring. Samples of asphalt emulsions derived from commercial asphalt emulsion B with 10 %m PCP and without PCP were tested using American Association of State Highway and Transportation Officials (AASHTO) Standard methods for Cationic Emulsified Asphalt (M 208, 2018), Table 2.

[0155] Table 2. AASHTO and ISSA test results for asphalt emulsions and blends of asphalt emulsion with a phase inverted liquid suspension of PCP-B.

[0156] Notes: a. at 25°C, b. US No.20 sieve, i.e. 850 pm, c. at 25°C under 100g load for 5 s duration d. at 25°C and elongation speed of 5 cm / min

[0157] A 10% blend of phase inverted liquid suspension of PCP in emulsion B satisfies all the AASHTO M208 specification limits for Cationic Emulsified Asphalt with seven of the ten properties almost unaffected, i.e. viscosity, storage stability, particle charge, sieve test, cement mixing, residue by distillation, oil by distillation. With an ash of 2.9 %m, 10% of PCP-B would be expected to increase ash content by approximately 0.3%, and indeed it does report an ash content of 0.60%, which is still well within specifications. Ductility and penetration are both reduced in the 10% blend to levels closer to the specification limit.

[0158] Samples of the cationic emulsions with and without PCP-B liquid suspension were tested by using three International Slurry Surfacing Association (ISSA) standard tests (https: / / www.slurry.org / page / TechnicalBulletins), Table 2, together with specification limits. Successful test specimens were made with the samples containing 10%m and 20%m PCP-B liquid suspension obtained from phase inverted wetcake, however the initial test mix with aggregate for 100%m C failed as it would not consolidate.

[0159] The Wet Track Abrasion Toss test (ISAA TB 100) measures the wearing qualities of slurry surfacing systems under wet abrasion conditions. The emulsion, aggregate and cement is shaped in a mold. This sample is dried, immersed in a 25°C water bath, then mechanically abraded under water with a weighted rubber hose. The loss in weight per unit area is calculated. After a one-day soak, the abrasion loss was almost 40% lower for emulsion B with 10 %m liquid suspension PCP- B additive (10.6 g / ft2 / 114.1 g / m2), than that without PCP-B additive (17.6 g / ft2 / 189.4 g / m2); both values are well below the 60 g / ft2(646 g / m2) specification maximum, indicating that replacement of just 10 %m of asphalt emulsion by a phase inverted liquid suspension of PCP-B results in a road surface that is more durable than one prepared with the conventional asphalt emulsion alone. Despite emulsion C failing the test, once the liquid suspension of PCP-B was added the abrasion loss results were well within specification for both 10 %m and 20 % level of addition. Thus, addition of phase inverted liquid suspensions of PCP are shown to improve the commercial emulsion C significantly to bring abrasion loss well within specification limits.

[0160] The Sand Adhesion Test (ISAA TB 109) is used to determine the maximum asphalt content of slurry surfacing systems by using a loaded wheel tester and measuring the weight of sand adhered to the wheel. Excess asphalt content may result in severe asphalt flushing and / or densification under heavy traffic loads. Unexpectedly superior performance was obtained for emulsion B containing 10 %m phase inverted liquid suspensions of PCP-B (30.2 g / ft2 / 325.1 g / m2) than that without phase inverted liquid suspension of PCP-B (48.0 g / ft2 / 516.7 g / m2); both are well below the 50 g / ft2(538 g / m2) maximum. Despite emulsion C failing the test, once phase inverted liquid suspensions of PCP-B were added the sand adhesion results were well within specification for both 10 %m and 20 % level of addition. Again, addition of phase inverted liquid suspensions of PCP improves the commercial emulsion C significantly to bring sand adhesion loss well within specification limits.

[0161] The Wet Cohesion Test (ISAA TB 139) is used to determine initial set and cure development of slurry surfacing systems as a function of torque over time and quantifies the time required before a slurry surfacing system may be subjected to straight rolling traffic. A slurry surfacing mixture is prepared and cast into appropriate molds; once the sample is firm enough to resist flow, the mold is removed, and torque values are recorded at specific intervals to determine cure development.

[0162] Satisfactory wet cohesion performance was obtained for emulsion B containing 10 %m phase inverted liquid suspensions of PCP-B with 14 kg.cm (Set) and 20 kg. cm (Traffic) values just meeting wet adhesion specifications. Despite emulsion C failing the test, once phase inverted liquid suspensions of PCP-B was added at 10 %m the wet cohesion results of 20 kg.cm (Set) and 23 kg.cm (Traffic) values were both well within specification. Although the addition of 20%m phase inverted liquid suspension PCP-B exceeded the Set specification, it falls slightly (18 kg.cm) below the Traffic limit (20 kg.cm) indicating that in this particular case phase inverted liquid suspensions of PCP-B is limited to an optimal value of between 10 %m and 20 %m. Addition of phase inverted liquid suspensions of PCP-B to emulsion D significantly improves the Set value from borderline (12 kg.cm) to well above (28 kg.cm) specification. A smaller improvement in the Traffic value was also observed as a resulting of adding phase inverted liquid suspensions of PCP- B to emulsion D from 28 kg.cm to 32 kg.cm.

[0163] Example 9: Phase-inverted liquid suspension of PCP wetcake blended with a laboratory prepared anionic asphalt emulsion D

[0164] Asphalt emulsion D with a solids content of 60%m was prepared from asphalt I, emulsifier A (2 %m) and water. The emulsifier and water were pre-mixed at 50°C and then combined with asphalt at 150°C in a bench-top colloid mill (JMS-60 from Wenzhou Kingpak International, Wenzhou, Zhejiang, China). In a colloid mill the blend to be processed is fed through a hopper into the mill, where it passes through the small gap (typically in the range of 0.05 to 1.5 mm) between a rotor (a rotating component with concentric teeth) and a stator, a stationary component. The particles are repeatedly broken down into smaller sizes from shearing, grinding and turbulence, and continuously circulate within the mill, resulting in a homogeneous product.

[0165] Anionic emulsion D was mixed with phase-inverted PCP-B wetcake (10 %m, calculated on a dry basis) as described in Examples 2 and 3 using 4 %m emulsifier A. Anionic emulsion D readily mixed with the inverted wetcake under low intensity stirring. Samples of this anionic emulsion with and without phase inverted liquid suspensions of PCP-B were tested using two International Slurry Surfacing Association (ISSA) standard tests: the Wet Track Abrasion Loss test (ISAA TB 100) and the Sand Adhesion Test (ISAA TB 109), Table Y. In addition, interlayer bond strengths were determined by Asphalt Testing Solutions & Engineering, LLC, Jacksonville, FL, USA. The results are shown in Table 2 above.

[0166] After a one-day soak, the abrasion loss was more than 30 % lower for emulsion D with additive of 10 %m PCP-B (15.5 g / ft2 / 166.8 g / m2), than that without PCP-B (22.3 g / ft2 / 240.0 g / m2); both values are well below the 60 g / ft2specification maximum. This unexpected result indicates that replacement of 10 %m of asphalt by a liquid suspension of phase inverted PCP wet cake results in a road surface that is considerably more durable than one prepared with the conventional asphalt emulsion alone. Superior sand adhesion performance was obtained for emulsion D containing 10 %m PCP-B (13.0 g / ft2 / 139.9 g / m2) than that without PCP-B (21.3 g / ft2 / 229.2 g / m2); both are well below the 50 g / ft2maximum threshold.

[0167] To establish if addition of phase inverted liquid suspensions of PCP-B compromise the adhesion properties of emulsion D, the interlayer bond strength (IBS) between two layers of asphalt pavement was determined by Florida Dept, of Transportation (DoT) Method FM 5-599. This method determines the IBS by applying a load in a shearing mode to a cored sample, in this case emulsion D with and without the phase inverted liquid suspension of 10 %m piPCP-B. Triplicate measurements are made and the average values for load and IBS are given in Table 3 below.

[0168] Table 3. Adhesion properties of emulsion D.

[0169] The tackless track specification limit set by Florida DoT is 100 psi (689.5 kPa) minimum with slightly lower limit of 80 psi (551.6 kPa) during construction. Surprisingly, the reduction in IBS was much less than anticipated from substitution of 10% asphalt D by phase inverted liquid suspension of a PCP. Emulsion D with or without 10% phase inverted liquid suspension of PCP- B which were well above these specification thresholds.

[0170] Example 10: Preparation of an asphalt emulsion from a phase-inverted liquid suspension of PCP wetcake blended with asphalt in a colloid mill

[0171] Examples 6-8 illustrate the use of phase inverted liquid suspension of PCP as a component in the preparation of asphalt emulsions by blending with asphalt emulsions (method A in Figure 1). Here it is demonstrated how liquid PCP can be added to the aqueous feed into a colloid mill into which liquid asphalt I is added (method C in Figure 1).

[0172] PCP-B wet cake is combined in a 5-gallon ribbon blender (Vevor, Shanghai, China) with 4 %m emulsifier A and 1 %m of 35% hydrochloric acid to transform the solid wet cake into liquid PCP. This liquid PCP contains water from wetcake (42.75 %m), emulsifier (2.4 %m) and hydrochloric acid (0.65 %m), thus 45.9% water content (54.1% solids) overall. The liquid PCP is then combined with the emulsion aqueous feed which contains 97 %m water, 2 %m emulsifier A and 1 %m of 35% hydrochloric acid at pH 2. The colloid mill itself (see example 9) and the PCP / aqueous feed mixture are both preheated at 50°C before introducing the PCP / aqueous blend into the mill. The asphalt I is preheated to 150°C, then added into the mill over a period of 30 seconds, followed by a further 30 seconds of mixing.

[0173] The cationic emulsion made in this manner had a viscosity of 19 cP at 62% solids and remained stable for over 2 weeks at ambient temperature.

[0174] Example 11: Density determination for PCP particles, phase inverted liquid PCP and asphalt emulsions containing PCP

[0175] To determine the density of PCP-B, a weighed amount of PCP-B wet cake of known moisture content was introduced into a calibrated pycnometer with a 50 ml Specific Gravity Cup (Yuchengtech, China), and the remaining volume filled with water. The full pycnometer was externally cleaned, weighed and the volume of PCP-B in the unit calculated. The resultant density of the dry PCP in the wet cake is 1254 kg / m3. In a similar manner, densities of the anionic and cationic liquid PCPs prepared as in examples 2 and 5, and of the cationic asphalt emulsion B and the anionic asphalt emulsion D, were measured. In addition, a series of anionic and cationic emulsions were prepared at 60 %m - 65 %m solids, in which 0 %m, 10 %m and 20 %m of the asphalt was replaced by PCP-B in the form of phase inverted wet cake. Their densities was measured using a 100 cc volumetric flask. A long-necked funnel was used to introduce the emulsion into the flask to minimize wetting of the neck of the flask. From the known volume of the calibrated flask and weight of emulsion in the full flask, density was calculated.

[0176] The resultant values were compared with calculated density values, Table 4.

[0177] Table 4. Measured and calculated densities of PCP, phase inverted liquid PCPs, and asphalt emulsions with and without PCP. n.a. not applicable

[0178] Measured densities of cationic and anionic phase inverted liquid PCP are very close to the density calculated from the weighted average of the component specific gravities (density of emulsifier A and 35% hydrochloric acid are taken are 1090 kg / m3and 1180 kg / m3respectively). The measured densities of the asphalt emulsions blended with liquid PCP rise linearly with increasing PCP dosage, and they are similar to the calculated values. This density increase is quite small:

[0179] • Addition of 20% PCP as liquid PCP to emulsion B increases density by just 17 kg / m3

[0180] • Addition of 20% PCP as liquid PCP to emulsion D increases density also by just 17 kg / m3

[0181] Although particular embodiments of the invention have been disclosed herein in detail, this has been done by way of example and for the purposes of illustration only. The aforementioned embodiments are not intended to be limiting with respect to the scope of the appended claims, which follow. It is contemplated by the inventors that various substitutions, alterations, and modifications may be made to the invention without departing from the spirit and scope of the invention as defined by the claims.

[0182] Embodiments of invention are further exemplified in the following non-limiting clauses:

[0183] 1. A process for manufacturing a liquid suspension of a purified coal product (PCP) comprising the steps of:

[0184] - providing a solid PCP wetcake, wherein the PCP is comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and a moisture content of at least 20%m; and

[0185] - inducing a phase inversion of the solid PCP wetcake by addition of a minor amount of an emulsifier.

[0186] 2. The process of clause 1 , wherein the PCP wetcake has a moisture content of at least 30%m, optionally at least 40%m, suitably at least 50%m, typically at least 60%m.

[0187] 3. The process of clause 1 or 2, wherein the PCP is comprised of coal particles having a d90 particle size of less than 25 microns.

[0188] 4. The process of any previous clause, wherein the liquid suspension of PCP exhibits properties of a hydrosol.

[0189] 5. The process of any previous clause, wherein the emulsifier is added in an amount of less than 30%m, optionally less than 20%m, suitably less than 10%m of the total of the combined mass of the solid PCP wetcake and emulsifier. 6. The process of clause 5, wherein the emulsifier is added in an amount of around 5%m of the total of the combined mass of the solid PCP wetcake and emulsifier.

[0190] 7. The process of any previous clause, wherein the emulsifier comprises an anionic substance.

[0191] 8. The process of any one of clauses 1 to 6, wherein the emulsifier comprises a cationic substance.

[0192] 9. The process of any one of clauses 1 to 6, wherein the emulsifier comprises an amphoteric substance.

[0193] 10. The process of any previous clause, wherein no additional carrier water is added to form the liquid suspension.

[0194] 11. The process of any previous clause, wherein the liquid phase of the liquid suspension is substantially comprised of the moisture content of the solid PCP wetcake.

[0195] 12. The process of any previous clause, wherein the liquid suspension has a dynamic viscosity of not more than 600 cP, suitably not more than 400 cP and optionally around 200 cP.

[0196] 13. The process of any previous clause, wherein the liquid suspension of PCP has a total water content inclusive of inherent moisture of not more than 55%m.

[0197] 14. The process of any previous clause, wherein the liquid suspension of PCP is stable and exhibits substantially no settlement for a period of at least 24 hours after manufacture.

[0198] 15. The process of any previous clause, wherein the emulsifier is added via a low energy mixing step.

[0199] 16. The process of any previous clause, wherein the solid PCP wetcake comprises a coal selected from: a bituminous coal; a sub-bituminous coal; or lignite.

[0200] 17. The process of any previous clause, wherein the solid PCP wetcake comprises and ash content of less than around 5%m; typically less than 3%m, suitably less than 2%m, optionally not more than l%m. 18. A pumpable liquid suspension of PCP obtainable according to the process of any one of clauses 1 to 17.

[0201] 19. A liquid suspension of PCP, wherein the PCP is comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and wherein the liquid suspension has a total water content inclusive of inherent moisture of not more than 55%m.

[0202] 20. The liquid suspension of clause 19, wherein the liquid suspension has a dynamic viscosity of not more than 600 cP, suitably not more than 400 cP and optionally around 200 cP.

[0203] 21. The liquid suspension of clauses 19 or 20, wherein the liquid suspension is the result of a phase inversion of a solid PCP wetcake.

[0204] 22. The liquid suspension any one of clauses 19 to 21, wherein the liquid suspension further comprises an emulsifier in an amount of less than 30%m, optionally less than 20%m, suitably less than 10%m of the total of the combined mass of the liquid suspension.

[0205] 23. The process of clause 22, wherein the emulsifier is present in an amount of around 5%m of the total of the combined mass of the liquid suspension.

[0206] 24. A method of using a liquid suspension of PCP obtainable according to the process of any of clauses 1 to 17 as an additive in the manufacture of an asphalt emulsion, the method comprising combining the liquid suspension of PCP with a feedstock of the asphalt emulsion or with the asphalt emulsion itself.

[0207] 25. A method of using the liquid suspension of PCP of any of clauses 1 to 17 as an additive in the manufacture of an asphalt emulsion, the method comprising combining the liquid suspension with a feedstock of the asphalt emulsion or with the asphalt emulsion itself.

[0208] 26. A process for the manufacture of a PCP-asphalt emulsion, the process comprising combining a PCP additive with a feedstock of the asphalt emulsion or with an asphalt emulsion itself, wherein PCP additive comprises a liquid suspension of PCP, and wherein the PCP is comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and wherein the liquid suspension has a total water content inclusive of inherent moisture of not more than 55%m and a dynamic viscosity of not more than 600 cP.

[0209] 27. A composition comprising: a phase inverted liquid suspension of a PCP is comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and a moisture content of at least 20%m; and an anionic emulsifier; wherein the composition has a total water content of less than 60%m.

[0210] 28. An asphalt emulsion comprising the composition of clause 27 in an amount of up to 10%m, suitably up to 15%m, typically up to 20%m, optionally up to 30%m.

[0211] 29. A composition comprising: a phase inverted liquid suspension of a PCP comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and a moisture content of at least 20%m; a cationic emulsifier; and hydrochloric acid wherein the composition has a total water content of less than 60%m.

[0212] 30. An asphalt emulsion comprising the composition of clause 29 in an amount of up to 10%m, suitably up to 15%m, typically up to 20%m, optionally up to 30%m.

Claims

CLAIMS1. A process for manufacturing a liquid suspension of a purified coal product (PCP) comprising the steps of:- providing a solid PCP wetcake, wherein the PCP is comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and a moisture content of at least 20%m; and- inducing a phase inversion of the solid PCP wetcake by addition of a minor amount of an emulsifier.

2. The process of claim 1, wherein the PCP wetcake has a moisture content of at least 30%m, optionally at least 40%m, suitably at least 50%m, typically at least 60%m.

3. The process of claim 1, wherein the PCP is comprised of coal particles having a d90 particle size of less than 25 microns.

4. The process of claim 1, wherein the liquid suspension of PCP exhibits properties of a hydrosol.

5. The process of claim 1, wherein the emulsifier is added in an amount of less than 30%m, optionally less than 20%m, suitably less than 10%m of the total of the combined mass of the solid PCP wetcake and emulsifier.

6. The process of claim 5, wherein the emulsifier is added in an amount of around 5%m of the total of the combined mass of the solid PCP wetcake and emulsifier.

7. The process of claim 1, wherein the emulsifier comprises an anionic substance.

8. The process of claim 1, wherein the emulsifier comprises a cationic substance.

9. The process of claim 1, wherein the emulsifier comprises an amphoteric substance.

10. The process of claim 1, wherein no additional carrier water is added to form the liquid suspension.

11. The process of claim 1, wherein the liquid phase of the liquid suspension is substantially comprised of the moisture content of the solid PCP wetcake.

12. The process of claim 1, wherein the liquid suspension has a dynamic viscosity of not more than 600 cP, suitably not more than 400 cP and optionally around 200 cP.

13. The process of claim 1, wherein the liquid suspension of PCP has a total water content inclusive of inherent moisture of not more than 55%m.

14. The process of claim 1, wherein the liquid suspension of PCP is stable and exhibits substantially no settlement for a period of at least 24 hours after manufacture.

15. The process of claim 1, wherein the emulsifier is added via a low energy mixing step.

16. The process of claim 1, wherein the solid PCP wetcake comprises a coal selected from: a bituminous coal; a sub-bituminous coal; or lignite.

17. The process of claim 1, wherein the solid PCP wetcake comprises and ash content of less than around 5%m; typically less than 3%m, suitably less than 2%m, optionally not more than l%m.

18. A pumpable liquid suspension of PCP obtainable according to the process of claim 1.

19. A liquid suspension of PCP, wherein the PCP is comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and wherein the liquid suspension has a total water content inclusive of inherent moisture of not more than 55%m.

20. The liquid suspension of claim 19, wherein the liquid suspension has a dynamic viscosity of not more than 600 cP, suitably not more than 400 cP and optionally around 200 cP.

21. The liquid suspension of claim 19, wherein the liquid suspension is the result of a phase inversion of a solid PCP wetcake.

22. The liquid suspension of claim 19, wherein the liquid suspension further comprises an emulsifier in an amount of less than 30%m, optionally less than 20%m, suitably less than 10%m of the total of the combined mass of the liquid suspension.

23. The process of claim 22, wherein the emulsifier is present in an amount of around 5%m of the total of the combined mass of the liquid suspension.

24. A method of using a liquid suspension of PCP obtainable according to the process of claim 1 as an additive in the manufacture of an asphalt emulsion, the method comprising combining the liquid suspension of PCP with a feedstock of the asphalt emulsion or with the asphalt emulsion itself.

25. A method of using the liquid suspension of PCP of claim 19 as an additive in the manufacture of an asphalt emulsion, the method comprising combining the liquid suspension with a feedstock of the asphalt emulsion or with the asphalt emulsion itself.

26. A process for the manufacture of a PCP-asphalt emulsion, the process comprising combining a PCP additive with a feedstock of the asphalt emulsion or with an asphalt emulsion itself, wherein PCP additive comprises a liquid suspension of PCP, and wherein the PCP is comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and wherein the liquid suspension has a total water content inclusive of inherent moisture of not more than 55%m and a dynamic viscosity of not more than 600 cP.

27. A composition comprising: a phase inverted liquid suspension of a PCP is comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and a moisture content of at least 20%m; and an anionic emulsifier; wherein the composition has a total water content of less than 60%m.

28. An asphalt emulsion comprising the composition of claim 27 in an amount of up to 10%m, suitably up to 15%m, typically up to 20%m, optionally up to 30%m.

29. A composition comprising:a phase inverted liquid suspension of a PCP comprised of coal particles having an average particle size of at most 10 microns and a d90 of less than 100 microns, an ash content of less than around 8%m, and a moisture content of at least 20%m; a cationic emulsifier; and hydrochloric acid wherein the composition has a total water content of less than 60%m.

30. An asphalt emulsion comprising the composition of claim 29 in an amount of up to 10%m, suitably up to 15%m, typically up to 20%m, optionally up to 30%m.

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