GB2549093B

GB2549093B - Natural asphalt pellets

Info

Publication number: GB2549093B
Application number: GB1605654.1A
Authority: GB
Inventors: Caldwell Neil; Porritt Gary
Original assignee: Cnrg Tech Ltd
Current assignee: Cnrg Tech Ltd
Priority date: 2016-04-04
Filing date: 2016-04-04
Publication date: 2019-08-21
Anticipated expiration: 2036-04-04
Also published as: GB2549093A

Description

NATURAL ASPHALT PELLETS FIELD OF THE INVENTION

The present invention relates to a composition and method for the pelletisation of natural asphalts such as Gilsonite and more specifically to a composition and method for the pelletisation of Gilsonite for use as a performance enhancing agent in asphalt / bitumen mixes. i

BACKGROUND

Gilsonite, also known as Uintahite or asphaltum, is a natural mineral asphalt mainly found in the Uintah Basin of Utah and Colorado, United States. It is a naturally-occurring, solid hydrocarbon bitumen. Although Mineral As^lt occurs in other locations, Utah is the main place to date where commercr quantities of this particular quality of mineral asphalt (Gilsonite) have been four.o. Other natural asphalts include lake asphalt such as Trinidad asphalt and rock asphalt and asphaltities such as glance pitch (also known as manjak) and grahamite.

For ease of description we will hereafter refer to just Gilsonite but it is to be understood that when referring to Gilsonite we mean to include only the natural asphalts Uintahite, asphaltum, lake asphalts such as Trinidad asphalt and rock asphalt and asphaltities such as glance pitch (also known as manjak) and grahamite.

Gilsonite is mined in underground shafts and resembles shiny black obsidian. Discovered in the 1860s, it was first marketed as a lacquer, electrical insulator, and waterproofing compound about twenty-five years later by Samuel H. Gilson. There is no quality definition for Gilsonite; accordingly any mineral asphalt may be described as Gilsonite.

Whilst Gilsonite has many uses and applications, including in the printing ink industry and in oil drilling, a major application is as a performance enhancing agent for asphalt/bitumen mixes. Gilsonite can partially or totally replace, or complement, the use of SBS polymers in modified asphalts at a fraction of the cost.

Gilsonite-modified asphalts have higher stability, reduced deformation, reduced temperature susceptibility and increased resistance to water stripping than non-modified asphalts. Gilsonite is also used to make both solvent-based and emulsion pavement sealers with superior appearance and weathering properties.

Gilsonite, when mined is generally delivered either in powder or rock form. Because of this, the use of the Gilsonite raw material in these various manufacturing processes is problematic. As a rock it needs to be crushed into a powder for processing and once in powder form the Gilsonite material becomes explosive under certain conditions. Accordingly, the commercial use of Gilsonite is significantly restricted due to health and safety legislation and the high cost of modifying asphalt / bitumen production plants to accept Gilsonite powder.

Providing the Gilsonite in a pellet form would greatly reduce the handling issues and eliminate the explosion dangers of processing Gilsonite in a powder form and greatly reduce the cost of modification of asphalt / bitumen production plants to allow for the addition of Gilsonite into asphalt / bitumen products.

It is known to produce Gilsonite in pellet form by means of a hot pelletising process specifically the steps of melting the Gilsonite and then extruding in the molten form, cooling and cutting the resultant extruded form into pellet sized pieces.

The prior art hot pelletising process is expensive in terms of energy consumption to produce the pellet. The high density of the resulting pellet also means that it requires high energy consumption to be melted when subsequently added to a asphalt/bitumen mix.

It is an aim of embodiments of the present invention to at least partially mitigate the disadvantages of the hot pelletising process, by producing Gilsonite pellets of a composition to enable production by means of “cold pelletising process”, not requiring the need to melt the Gilsonite and thereby saving on the cost of the energy required to melt the Gilsonite during the palletisation process.

It is a further aim of embodiments of the present invention, to produce Gilsonite pellets of a lower density than that obtained from the hot pelletising process, thereby reducing the energy requirement to melt the pellet when subsequently added to an asphalt / bitumen mix.

It is a further aim of embodiments of the present invention to provide the introduction of additional binding agents into a Gilsonite pellet providing advantageous properties when the Gilsonite pellet is subsequently added to an asphalt / bitumen mix for use in products such as emulsion products such as non-ionic cationic and anionic emulsions or for use in recycling and soil stabilisation products.

STATEMENT OF THE INVENTION

In a first aspect of the invention there is provided a composition for pelletised natural asphalt (specifically one or more from the following list: Uintahite, asphaltum, lake asphalts such as Trinidata asphalt and rock asphalt and asphaltities such as glance pitch (also known as manjak) and grahamite comprising: between 90% and 99% by weight of natural asphalt, and between 1 % and 10% by weight of one or more tree by-product(s) from lignin, lignosulphate, tall oil or tall oil pitch.

In a second aspect of the invention there is provided a method for pelletising natural asphalt as specified in claim 5 comprising the steps of providing a natural asphalt powder to feed a mesh filtering system to produce a filtered natural asphalt powder; blending/mixing the filtered natural asphalt powder with other ingredients such as adhesion agents or polymers and one or more tree by-product(s) (lignin, lignosulphate, tall oil or tall oil pitch) and water to produce a blended mixture; providing the blended mixture to the agglomeration / pelletising chamber; and providing the pellets to a drying/baking oven to remove the water, wherein the step of blending/mixing the filtered natural asphalt powder with one or more tree by-products and water comprises the steps of: providing between 80% and 90% by weight of natural asphalt; providing between 10% and 15% by weight of water; and providing between 1% and 10% by weight of tree by-product(s).

Embodiments of the invention have the advantage that the tree by-product(s) surprisingly provide a means of producing a pellet of Gilsonite without the heat energy requirements of a conventional hot pelletisation process which requires melting of the Gilsonite powder.

Embodiments of the invention have the additional advantage that the tree byproducts) increase the viscosity of the solution producing a better formed pellet.

Embodiments of the invention have a yet further advantage that the tree byproducts) act as a binder to hold the pellet together.

Embodiments of the invention have a yet further advantage that the resulting pellet has a lower density and requires less energy to melt in a subsequent process using the pellet, that pellets made by the conventional hot palletisation process.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to the accompanying figure in which:

Figure 1 is a simplified functional block diagram of the method of processing pelletised Gilsonite according to one or more embodiments of the present invention.

DETAILED DESCRIPTION A composition for pelletised Gilsonite in accordance with the present invention may comprise Gilsonite powder 10 and one or more tree by-product(s) 15.

The one or more tree by-product(s) may be one or more of lignin, calcium lignosulphonate, sodium lignosulphonate, tall oil or tall oil pitch from 1% up to approximately 10% by weight of the composition.

The particular one or more tree by-product(s) may be selected according to the intended application of the Gilsonite pellet, specifically whether the end application is asphalt and macadam manufacture or asphalt and macadam maintenance. A particularly useful composition may comprise between 93% and 97% by weight of Gilsonite and between 7% and 3% by weight of the one or more tree by-product(s).

An especially useful composition may comprise approximately 95.2% by weight of Gilsonite and 4.8% by weight of the one or more tree by-product(s).

To begin the process of pelletising the Gilsonite powder 10, the Gilsonite powder 10 should be provided by a feed tank 20 that is connected to a mesh filtering system 25. However it should be clearly understood that the Gilsonite powder 10 may also be delivered into the mesh filtering system 25 directly from a transport truck, or any other suitable mode of transportation, that may be connected to the mesh filtering system 25.

The mesh filtering system 25 comprises a metal screen where any foreign objects from the mining process, aggregate impurities and oversized products are removed and discarded. A size 16 mesh may be used in the mesh filtering system 25 although other mesh sizes are useful.

The filtered Gilsonite powder is then passed to a blending/mixing chamber 30 where it is mixed with metered amounts of other products such as adhesion agents or polymers 35 and the one or more tree by-product(s) 15 and water 40 each fed through a metering device 45 at a prescribed rate in order to deliver the binding medium for the Gilsonite powder. A particularly useful blended mixture comprises between 80% and 90% by weight of natural asphalt, between 10% and 15% by weight of water and between 1% and 10% by weight of tree-by-products.

The blended mixture is fed to an agglomeration/pelletising chamber 50.

The agglomeration/pelletising chamber 50 could be a “pin mixer” such as the type manufactured by Mars Minerals in their range of pin mixers A-150 through A-418.

Alternatively the agglomeration/pelletising chamber 50 could be a “pin mixer” such as the type manufactured by FEECO in their range of pin mixers models 0.25m3/hour up to 63.0 m3/hour.

Alternatively the agglomeration/pelletising chamber 50 could be a “disc pelletiser” such as the type made by Mars Minerals in their models P-30 through to P-250 with capacities of 0.5m3/hour up to 99 m3/hour.

Other types of agglomeration/pelletising chamber 50 would also be useful such as Drum Pelletisers or Briquette equipment with capacities of 0.5m3/hour up to 56 m3/hour.

Alternatively the agglomeration/pelletising chamber 50 could be a combination of a “pin mixer” and a “disc pelletiser” or “drum pelletiser”.

The agglomerated/pelletised material from the agglomeration/pelletising chamber 50 is then fed to a dryer/baking oven 55 where the pellets are dried and baked in order to reduce the moisture content of the pelletised Gilsonite composition in order to harden the material for subsequent blending and transportation.

Following the drying/baking process the Gilsonite pellets may be fed into a second blending/mixing chamber 60 where non-Gilsonite pellets 65 could be fed through a feed hopper 70 into the second blending/mixing chamber 60 to be blended with the Gilsonite pellets to form specific formulations for various use.

The blended pellets may then be fed through a second mesh filtering system 75, the size of the mesh selected to separate out the pellets according to size.

After the blended pellets have been filtered by size they are fed for packing in a bagger 80 before being ready for transportation.

Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of the words, for example “comprising” and “comprises”, means “including but not limited to”, and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Claims

» * NATURAL ASPHALT PELLETS CLAIMS:

1. A composition for a pelletised natural asphalt (specifically one or more from the following list: Uintahite, asphaltum, lake asphalts such as Trinidad asphalt and rock asphalt and asphaltities such as glance pitch (also known as manjak) and grahamite) comprising: between 90% and 99% by weight of natural asphalt, and between 1% and 10% by weight of one or more tree by-product(s) (specifically one or more from lignin, lignosulphate, tall oil or tall oil pitch).

2. The composition of claim 1, wherein the composition is composed of: between 93% and 97% by weight of natural asphalt, and between 7% and 3% by weight of one or more tree by-product(s).

3. The composition of claim 1, wherein the composition is composed of: approximately 95.2% by weight of natural asphalt, and approximately 4.8% by weight of one or more tree by-product(s).

4. A composition of any preceding claim, further comprising between 1% and 10% by weight of an adhesion agent or polymer

5. A method for pelletising a natural asphalt asphalt (specifically one or more from the following list: Uintahite, asphaltum, lake asphalts such as Trinidad asphalt and rock asphalt and asphaltities such as glance pitch (also known as manjak) and grahamite) comprising the steps of: providing the natural asphalt powder to feed a mesh filtering system to produce a filtered natural asphalt powder; blending/mixing the filtered natural asphalt powder with other ingredients adhesion agents or polymers and one or more tree by-product(s) I V (specifically one or more from lignin, lignosulphate, tall oil or tall oil pitch), and water blended mixture; providing the blended mixture to an agglomeration/pelletising chamber; and providing the pellets to a dryer/baking oven to remove the water; wherein the step of blending/mixing the filtered natural asphalt powder with one or more tree by-products and water comprises the steps of: providing between 80% and 90% by weight of natural asphalt; providing between 10% and 15% by weight of water; and providing between 1% and 10% by weight of tree by-product(s).

6. The method of claim 5 wherein the one or more tree by-product(s) is either calcium lignosulphonate or sodium lignosulphonate or a mixture of calcium lignosulphonate and sodium lignosulphonate.

7. The method of claims 5 or 6, further comprising the steps of: feeding the dried natural asphalt pellets output from the dryer/baking oven into a second blending/mixing chamber; feeding non- natural asphalt pellets into a second blending/mixing chamber; and blending the pellets to form a blended pellet mixture, the pellet mixture being optimised for different application.

8. The method of claim 7, wherein the non- natural asphalt pellet comprises a polymer pellet.