Patent Application
20150013271
(1) Field of the Invention
The invention relates to the preparation of a bituminous composition, such as asphalt, which is prepared, cooled and packaged for subsequent transport and use at a work cite, such as a road or highway. The invention relates to the preparation of a bituminous composition, such as asphalt, modified asphalt, or engineering asphalts, which is prepared, cooled and packaged for subsequent transport and blending or reaction and use at a work cite, such as a road or highway, roofing manufacturing unit, cable manufacturing unit and other types of manufacturing and processing units.
(2) Brief Description of the Prior Art
As used herein, bitumen, bitumen composition and asphalt are synonymous. Bitumen is completely soluble in carbon disulfide, and composed primarily of a mixture of highly condensed polycyclic aromatic hydrocarbons. Asphalt is most commonly modeled as a colloid, with asphaltenes as the dispersed phase and maltenesmateria as the continuous phase (though there is some disagreement amongst chemists regarding its structure). Although a considerable amount of work has been done on the two to discover the chemical composition of asphalt, it is exceedingly difficult to separate individual hydrocarbon in pure form and it is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large
Most natural bitumens contain sulfur and several heavy metals, such as nickel, vanadium, lead, chromium, mercury, arsenic, selenium, and other toxic elements Bitumens can provide good preservation of plants and animal fossils.
Asphalt/bitumen can sometimes be confused with “tar”, which is a similar black, thermoplastic material produced by the destructive distillation of coal. During the early and mid-20th century when town gas was produced, tar was a readily available product and extensively used as the binder for road aggregates. The addition of tar to macadam roads led to the word tarmac, which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, asphalt/bitumen has completely overtaken the use of tar in these applications. Other examples of this confusion include the La Brea Tar Pits and the Canadian tar sands. Pitch is another term mistakenly used at times to refer to asphalt/bitumen, as in Pitch Lake.
Natural deposits of asphalt/bitumen include lakes such as the Pitch Lake in Trinidad and Tobago and Lake Bermudez in Venezuela, Gilsonite, the Dead Sea, asphalt/bitumen-impregnated sandstones known as bituminous rock and the similar “tar sands”. Asphalt/bitumen was mined at Ritchie Mines in Macfarlan in Ritchie County, West Virginia in the United States from 1852 to 1873. Bituminous rock was mined at many locations in the United States for use as a paving material, primarily during the late 1800s.
Asphalt/bitumen can be separated from the other components in crude oil (such as naphtha, gasoline and diesel) by the process of fractional distillation, usually under vacuum conditions. A better separation can be achieved by further processing of the heavier fractions of the crude oil in a de-asphalting unit, which uses either propane or butane in a supercritical phase to dissolve the lighter molecules which are then separated. Further processing is possible by “blowing” the product: namely reacting it with oxygen. This makes the product harder and more viscous.
Asphalt/bitumen is typically stored and transported at temperatures around 150° C. (300° F.). Sometimes diesel oil or kerosene are mixed in before shipping to retain liquidity; upon delivery, these lighter materials are separated out of the mixture. This mixture is often called “bitumen feedstock”, or BFS, or bitumen or asphalt compositions. Some dump trucks route the hot engine exhaust through pipes in the dump body to keep the material warm. The backs of tippers carrying asphalt/bitumen, as well as some handling equipment, are also commonly sprayed with an agent before filling to aid release. Diesel oil is no longer used as a release agent due to environmental concerns.
Heretofore, the manufacture of bitumen compositions has required heating of the additives and the maintaining of the produced composition at elevated temperatures even as the resultant composition is being transported to a job cite, such as an area near the building of a road or highway, or airport runway, or roofing products manufacturing unit, or bituminous products process plants or the like. This becomes extremely problematic where the work cite is in a location far away from the manufacturing facility, requiring considerable time for transporting the bitumen composition by truck, barge or ship. The bitumen composition must be heated continuously during the transport step and storage. Where the job cite is overseas, the problem is compounded, oftentimes requiring the building and operation of a substantial manufacturing facility far from readily available sources of bitumen or additives for the formation of the ultimately desired composition.
Asphalt or bitumen is a thermoplastic material, a consistency of peanut butter or harder at ambient temperatures. It is a brittle solid at cold temperatures and liquid at high temperatures. It is easier and more cost effective to process most asphalts/bitumens in the liquid form.
The present invention addresses problems associated with the manufacture, storage and delivery of bituminous compositions such that the necessity for continued heating during transportation and delivery to the work cite is eliminated.
The present invention provides for the preparation of a carefully defined cold blend/mixture of bitumen compositions that, when subsequently heated and mixed and/or blended at a hot mix plant yield a composition that meets the project, job and/or agency binder specifications. Some of the benefits of such a process are:
In accordance with the present invention, the majority of the work and complex formula development is done using the teachings herein, and the end user simply heats blends/mixes and uses the resultant product to make hot mix pavement, or in other uses.
In the present invention, bulk cold packed containerized pre-blended modified asphalt/bitumen is prepared for subsequent use in asphalt, cold patches and/or but not limited to roofing products. Bulk cold packed containers in the form and various sizes of polyolefin bags, big bags, jumbo bags, polybags, bitumen transportation containers (commonly referred to as Bitutainers or ISO Containers) or steel drums, as commonly used in the industry, provides a means to transport and use modified bitumen, PMB's, into areas not equipped for common bulk transportation by truck, rail or ship or simply as a preferred form by the user.
The cold packaged containerized bitumen is formulated to contain non-reacted or prepared mixtures of bitumen, additives, polymers, modifiers, extenders, and associated ingredients that at the use site are melted and blended or added to host bitumen and blended in proportions yielding bitumen meeting project specifications or requirements. The bulk cold packed containerized pre-blended bitumen is prepared using a process involving and combining a specially designed steel belt process conveyor system which combines selected ingredients into a non-reacted mixture which in turn is feed into an extruder forming the mixture into morphology suitable for filling the type of bulk container used.
The containers, ‘Bitutainers’ are available in various sizes from 50 gals to 5,000+ gals and capabilities. Larger ISO type containers with capacities up to 30 MT are reusable and equipped for various types heating and pouring/pumping capabilities. Smaller drums, in the 150-250 Kg capacity range typically non-usable, require a heating and pouring system such as a decanter. Polybags in the 25-2,000 Kg capacity are constructed from materials which permit the entire bag to be added to hot bitumen, the entire package with contents are used, there is no waste.
The pre-blended modified asphalt may be specifically formulated to meet specifications or project requirements and be suitable for direct use through heating and mixing or may be in a concentrate form for addition and letdown in a host hot bitumen for mixing.
I intend for the following words and phrases to have the following meanings, as used in the claims and all other parts of the specification:
A cold blending and containerizing method and apparatus are disclosed and claimed for preparing a bitumen composition for subsequent transport to a selected work cite and final preparation. Into a first receptacle is introduced a pre-selected quantity of one or more additives for the formation of the composition. The additives are then mixed and/or heated within the receptacle to form the bitumen composition. The bitumen composition is exposed to means for reducing the temperature of the composition to cool the composition to a pre-determined temperature, such as by use of one or more fluids, preferably delivered onto at least one side of a rotating belt, and thereafter packaging the cooled bitumen composition into at least one container for transport to a selected work cite.
As an illustration of an asphalt composition preparation, cooling and packaging which would use the present apparatus and method, the following composition formulas may be prepared using the additives as described below:
Now with reference to the Figs., there is shown in
Optionally, all additives may be pre-blended (as opposed to reacted) and deposited onto the belt as a homogenous mixture of bitumen. If polymers are used, they have not been dissolved nor have they been cross-linked.
Typically, the asphalt initially will be hot, such as 200-350° F. The polymers and related additives may be dry, particulate solids at ambient conditions. Any cross-linking agents may be powder sulfur, or oil extender or pelletized sulfur. The base asphalt may be a combination of asphalts and may include extender oils, and other additives such a PPA, polyphosphoric acid or other materials known to change the base asphalt properties and/or chemical composition.
It is assumed that at the work site, there are tanks or vessels to melt and mix the packaged blend of materials in a fashion suitable to yield the desired PMB. The melters, typically referred to as decanters, are packaged units sold for the purpose of melting and transferring the hot liquid bitumen to tanks for subsequent mixing, storage and delivery to the hot mix plant for combination with the aggregates.
Now, with reference to
The belt assembly 8 and cooling system may be as described in PS-452 ENG 10.2004, “Sandvik bitumen-asphalt packaging” system, the total disclosure of which is hereby incorporated herein, and which device is available from Sandvik Mining, World Trade Center, Tower C, 15th Floor, Strawinsky 1545, 107 XX Amsterdam, Netherlands. This system must be reconfigured in accordance with the present invention to accommodate the bitumen/asphalt and additives for the formation of the composition as disclosed herein.
Although the invention has been described herein, it should be understood that this is by illustration only, and that changes and modifications may be made to the apparatus and method which are well within the abilities of one having ordinary skill in the art but still remain within the scope, spirit and intent of the invention, and that scope of the invention is as defined in the claims, below.
