WO2010115240A1

WO2010115240A1 - Treatment of radioactive scale

Info

Publication number: WO2010115240A1
Application number: PCT/AU2010/000396
Authority: WO
Inventors: Cameron Wills
Original assignee: AGR ASIA PACIFIC Pty Ltd
Current assignee: AGR ASIA PACIFIC Pty Ltd
Priority date: 2009-04-08
Filing date: 2010-04-08
Publication date: 2010-10-14
Anticipated expiration: 2011-10-08

Abstract

The present invention relates to a plant and process for handling scale material containing naturally occurring radioactive material (NORM) that builds up on oilfield processing equipment. The invention involves breaking the scale material up into a size that is suitable for disposal offshore or for further processing. Suitably the plant can be housed and transported in a shipping container.

Description

TREATMENT OF RADIOACTIVE SCALE

FIELD OF THE PRESENT INVENTION

The present invention relates to a plant and process for treating and handling scale material that builds up on oilfield processing valves, pipes, tanks and other equipment items . The scale material on oilfield processing equipment typically contains Naturally Occurring Radioactive Material (NORM) . The manner in which NORM is handled with reference to environmental contamination and occupational health and safety issues is an issue for the oil and gas industry.

BACKGROUND OF THE PRESENT INVENTION

To date the majority of NORM produced in Australian is generated in the offshore petroleum production sectors of the oil industry of the Northern Territory and Western Australia. It is expected that some potential for NORM generation exists with respect to onshore applications, however the extent to which this occurs is unknown.

Scale material in oilfield pipes, vessels and fittings is a problem for petroleum operators. Specifically, the build up of scale restricts fluid flow, which in turn directly affects profitability of petroleum operations . Water plays an integral part in oil production. Prior to oil extraction, the environment of the formation water is static; and equilibrium exists. Oil production introduces a shift of this equilibrium through the venting of gases , reduction of temperatures and pressures, and alteration of pH.

Radium isotopes (principally Ra-226 and Ra-228) and their decay products exist in the formation water of oil reservoirs . The radium isotopes account for approximately 70% of the radioactivity of the scale formed in production operations around the world. The radionuclides are, under normal conditions, soluble in the formation water. At large depths, formation waters may be strongly saline and hot. In addition this water may be chemically reducing. These conditions favour the dissolution of radium along with other cations including those of Ca, Sr and Ba provided the sulphate concentrations are low. Radium is more soluble in the chloride rich brine, and is less likely to be found in sulphate rich brine . As the formation water approaches the surface and its temperature drops , precipitation occurs in piping that conveys the fluid to the surface and other surface equipment. Radioactive scales are then deposited throughout production systems from the sub-sea equipment through well heads , production headers and production trains to export lines and terminals .

Scale formation is further enhanced when incompatatible water such as injected seawater which may be high in sulphate, mixes with Barium and Strontium rich formation water. Radioactive salts are usually found to co- precipitate with Barium and Strontium, which are chemical analogues to radium, as sulphates. The solubility of these salts is very low and reduces further as the temperature drops and hence the salt precipitates in the form of scale. Depending on the variations in pressure, temperature and flow and geo-chemical conditions these radioactive salts selectively precipitate in a non- reversible manner in the form of Barium Radium Sulphate Ba (RA) SO4 and/or Stontium Radium Sulphate Sr (RA) SO4.

It is an object of the present invention to provide a plant and process for treating scale material, particularly scale material containing radio active material . SUMMARY OF THE PRESENT INVENTION

PROCESS

According to the present invention there is provided a process of treating scale material containing naturally occurring radioactive material, the process including the steps of: a) grinding the scale material to a particle size of less than 10mm diameter; and b) forming a slurry (or suspension) mixture containing the particulate material formed in step a) and liquid.

Throughout this specification the term "naturally occurring radioactive material" embraces the following elements either separately or in any possible combination: radium 226, radium 228, radon 222, uranium, thorium and any other daughter elements thereof.

Throughout this specification particle sizes are described in terms of a diameter or range of diameters. It will be appreciate that the diameter or range of diameters of a particle approximates the largest width or cross section measurement of a particle.

In an embodiment, the process further includes a fines separating step in which fine particles, preferably having a size up to 5mm and even more preferably having a size of less than or equal to 2mm are separated from the scale material to form a fine particles stream. The fines separation step may involve screening the scale material on a sieve having any suitable aperture, such as apertures in the range of 1 to 5mm, and even more suitably approximately 2mm apertures, and yet even more suitably to apertures in the range of 1 to 0.5mm. In an embodiment, the fines separation step is carried out prior to grinding of the scale material according to step a) .

The fine particles stream may be added directly to the slurry mixture formed according to step b) .

In an embodiment, the fines separation step includes spraying the fine particles with liquid. In the situation in which the fine separation step involves screening the fine particles, the fine particles may be sprayed with liquid after the particles have passed through the screen separator. Alternatively, the scale material may be sprayed as the scale material passes over the screen separator.

In an embodiment, the process further includes a coarse separating step in which coarse particles, preferably having a size of at least 30 to 80 mm in diameter and, suitably in the range of 40 to 50mm are separated from the scale material.

Suitably, the coarse separation step is carried out on the scale material prior to the scale material being subject to step a) .

Suitably, the coarse material separated in the coarse separation step is subjected to a pre-grinding step, suitably a manual grinding step, in which the coarse particles are broken to a size of less than or equal to 30 to 80 mm diameter and preferably, 40 to 50mm diameter. Once the coarse material has been subjected to the pre- grinding step, the pre-ground material may be ground according to the step a) . For example, the pre-grinding step may include manually hammering the coarse material on the coarse separation screen having apertures of 30 to 80mm.

The course material ground according to the pre-grinding step may then be ground according to step a) .

In an embodiment, grinding according to step a) includes wet milling the scale material . Wet milling reduces the chance of dust containing radioactive material from becoming airborne which, in turn, would be inhaled by workers. Suitably, the grinding step includes grinding the material to a particle size of less than 5mm and preferably to a particle size ranging from 1 to 2mm. Even more suitably, the grinding step includes grinding the material to a particle size range in which 90% of the material is grounded to less than 0.5mm.

In an embodiment, step b) includes forming a slurry having a radioactive activity of less than 1 becquerel (Bq) per gram.

The recommended ratio of radioactive material to liquid is dependant on the type of disposal method intended. One disposal method involves releasing the slurry at offshore locations. For example, to comply with the requirements of regulatory approval, it may be necessary for the slurry to be a dilute to a slurry mixture having a radioactive activity of less than 1 Bq per gram for radio nuclide and its daughters Ra 226 and RA 288.

In the situation in which the scale material contains residual hydrocarbon such as oils and waxes , the slurry may be further processed to separate phases of the slurry. For example, a hydrocarbon or hydrophobic phase, a liquid or aqueous phase, and a concentrate slurry phase or solid phase may be separated in a settling step prior to disposal of the slurry or solid phase. In another example, a hydrocarbon or hydrophobic phase may be separated from an aqueous or concentrated slurry phase containing the particulate material for disposal thereof.

The settling step may include the treatment of the slurry using any suitable multiphase dispersion chemicals . Moreover, the settling step may be carried out using phase separators such as those available from the CET-CO of Australia.

To facilitate separation of hydrocarbons from the remainder of the scale material, suitably step b) involves forming a slurry with minimum water content feeding the Cetco hydrocarbon separation system.

In a third disposal method, the slurry can be disposed of in an abandoned well. Once a well has been fully exploited of oil and/or gas, it is standard practice to cap the well with a concrete capping to prevent leakage of residual hydrocarbon material from the well into the environment .

In this situation, it is preferred that step b) include forming a slurry having a minimum amount of the liquid possible for a flowable material. For instance, the slurry may have total solid mass to liquid ratio in the range of 1 - 2 : 1.

In an embodiment of the invention, the process may also include feeding the slurry into the well bore and simultaneously or separately capping the well bore with concrete .

The liquid may be fresh drinking water or sea water. In an embodiment, the scale material may include any radioactive material including radium 226, radium 228, radon 222 , uranium and thorium and any daughter elements thereof .

In an embodiment, the process includes sampling the scale material and determining the mass or concentration of radioactive material (or NORM) in the scale material and determining the total amount of liquid to be added to form the slurry.

Once the amount or concentration of radioactive mass is known per handling unit, such as a storage container, the amount of liquid to be added to the scale material can be calculated.

In an embodiment, step b) involves adding the ground material of step a) and optionally the fine stream of particles and an amount of liquid, into a vessel and mixing. The amount of liquid to be added can be calculated based on the measured mass of radioactive material and a required radio active mass to liquid ratio as described above.

PLANT

According to the present invention there is also provided a plant that treats scale material containing naturally occurring radioactive material , the plant including : a grinding or milling machine that breaks scale material to a particle size of less than 10mm diameter; and a mixing vessel in which the scale material from the grinding or milling machine is mixed with liquid to form a slurry. In an embodiment, the grinding or milling machine supplies ground material directly into the mixing vessel. Suitably, the grinding or milling machine breaks the scale material to a particle size of preferably less than or equal to 5mm and preferably to a maximum diameter in the size range of 1 to 2mm. Even more preferably, the grinding or milling machine breaks the material to a particle size range such that 90% of the material is ground to less than 0.5mm.

In an embodiment, the plant also includes a fines separator having screen or sieve apertures of 10mm, suitably 5mm and even more suitably approximately 2mm that separates fine particles from the scale material. The fines separator is suitably located upstream of the grinding or milling machine so that the fines separator separates fine particles from the scale material and holds scale material on the screen to be fed to the grinding machine .

In an embodiment, the plant includes a channel or chute located at an underside of the fines separator screen, and one or more than one outlet that discharges liquid to wash the fine particles that have passed through the fine separator screen into the mixing vessel. Suitably, the outlet discharges liquid onto the channel or chute to wash the fine particles thereon into the mixing vessel.

Suitably, the outlet is arranged below the fines separator screen so as to spray liquid onto the fine particles as the fine particles descending from the fine screen separator onto the chute .

In an embodiment, the plant also includes coarse separator having screen or sieve apertures greater than 10mm and suitably in the range of 30 to 80mm, or even more suitable in the range of 40 to 50mm diameter. Ideally, the coarse separator has a screen on which manual hammering can be performed.

In an embodiment, the plant also includes a lifting mechanism that is adapted for lifting and emptying containers in which the scale material is stored, such as 44 gallon drums, or various sized plastic wheelie bins include 240 litre wheelie bins.

In an embodiment, the plant also includes a liquid distribution system that supplies fresh water or sea water to the mixing vessel and/or the outlet beneath the fines screen separator and/or the coarse screen separator and/or the wet milling machine.

In an embodiment, the plant may include a base on which the plant is supported the base is capable of being housed in a shipping container or a lower half thereof for transporting the plant. For instance the base can be connected to a crane for lift and lowering the plant into and out of a lower half of shipping container. An advantage provided by this aspect of the plant is that the plant can be readily transported to a desired located by ship, road or rail.

The plant of the present invention may also include any one or a combination of the features of the present invention described under the heading PROCESS.

According to the present invention there is also provided a transportable plant that can be housed inside a shipping container, the transportable plant including: a base on which the plant is supported so that the plant can be moved in and out of a shipper container by moving the base; a grinding or milling apparatus breaking scale material to a particle size of less than 10mm diameter; and a mixing vessel in which the scale material from the grinding or milling apparatus is mixed with liquid to form a slurry.

In embodiment, the base can be lowered into or out of a shipping container having an openable upper section . For example, a suitable shipping container is a container having lower and upper halves , and the plant can be loaded into the container by lowering the base into the lower half of the container.

The transportable plant of the present invention may also include any one or a combination of the features of the present invention described above under the heading PLANT or PROCESS.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings, of which:

Figure 1 is a flow diagram of a process according to an embodiment;

Figure 2 is a perspective view of a plant that is sized and configured to fit inside a conventional shipping container, wherein the plant is adapted for carrying out the process shown in Figure 1;

Figure 3 is perspective view of the plant shown in Figure 2 wherein the plant has been removed from the shipping container; and

Figure 4 is a side view of the plant shown in Figure 3.

DETAILED DESCRIPTION

The preferred embodiment of the present invention will now described with reference to the process shown in Figure 1 and a plant with reference to Figures 2 to 4 that embodies the process. As a matter of convenience, the same reference numerals have been used in all of the Figures to identify the same or substantially the same features.

Initially, scale material is removed from equipment items such as piping, valves, tanks and alike using conventional techniques such mechanical scrappers . The scale material is then typically stored in suitable containers 10 such as 44 gallon drums, or 240 litre wheelie bins until processing for disposal. The concentration of radioactive material is tested in each storage container and an appropriate mass of NORM (Naturally Occurring Radioactive Material) to liquid ratio determined based on the intended disposal method.

Figure 1 illustrates a flow diagram of the process for handling the scale material for disposal according to an embodiment of the present invention. In summary, the process includes a fines particle separation step via screen separator 11, a coarse particles separation step via course particle screen separator 15, and pre-grinding the coarse particles such as manual crushing and grinding on screen separator 15, followed by grinding the scale material to a desirable particle size range via a milling machine, suitably to a maximum size of the 1 to 2mm and mixing a slurry comprising the ground particles .

More specifically, once the NORM to liquid ratio is attained and the amount of liquid per storage container calculated, the contents of the storage container 10 is emptied onto a fine screen separator 11 having apertures preferably 2mm in size. Fine particles passing through the fine screen separator 11 are sprayed with water, either fresh water or sea water, via a spraying system 12 arranged below the fine screen separator 11. Fine particles passing through the screen 11 and water spray are channelled down via a chute 13 directly into a mixing vessel 14. Scale material held on the fine screen 11 moves across the screen 11 and down a second chute 14 onto a coarse particle separator 15.

The fine screen 11 may have any configuration but is preferably a stationary screen or a vibrating screen that is sloped from one end to an overflow end.

The chute 14 conveys the scale material held on the fines screen 11 to the coarse screen separator 15. The coarse screen separator 15 separates coarse sized particles that are held on the screen 15. The coarse screen separator 15 has an aperture size in the range of 40 to 80 mm, and preferably 50mm in size. The scale material passing through the coarse screen 15 having been held on the fine screen 11 and passing through the coarse screen has a particulate size in the range of the 2 to 50mm and is fed directly into a wet milling machine 16. The wet milling machine 16 may be any conventional grinding or milling machines such as a Sajo hammer milling machine. The milling machine 16 may also have any capacity and is suitably capable of processing in the range of 500 to 1000 kg/hr of scale material, and ideally approximately 800 kg/hr.

The coarse screen separator 15 is located above the milling machine 16 and preferably has a support capable of withstanding manual hammering or breaking of the coarse scale material held on the screen 15. When broken, the coarse scale material descends directly into the milling machine 16.

The milling machine 16 is operated to produce particle sizes of 2mm or less and which, together with the fine fraction, is fed directly into the mixing vessel 14 from a bottom outlet 17 of the milling machine 16. Water is dispensed onto the coarse screen 15 and in turn flows into the inlet of a milling machine 16 from a common storage tank (not shown in the drawings) via quick acting coupling 36 and piping 20.

Additional makeup water is also supplied into the mixing vessel 14 to form the slurry having the required mass of radioactive material to liquid ratio via piping 21. A suitable liquid level control system 22 may be employed to ensure that an adequate amount of water is fed into the mixing vessel 14. The mixing vessel 14 may also be mixed with a suitable motor driven stirring blade 33 and optional baffles on the inside of the mixing vessel 14. Sampling of the slurry may be conducted on a routine or on an as need basis to test the composition of the slurry.

If desired, additional chemicals may also be added to the mixing vessel, for example, dispersion or phase separation enhancers .

The slurry dispensed from the mixing vessel 14 may then be stored in storage containers and tanks until disposal. There are at least three disposal techniques currently in use that meet with regulatory approval. The first disposal technique involves mixing the slurry at a NORM to liquid ratio in order to obtain less than 1 Bq per gram activity of radio nuclide Ra 226 and Ra 228. A slurry of this composition, will facilitate disposal of the slurry offshore using conventional offshore dumping.

In the situation in which the scale material contains residual or otherwise significant quantities of hydrocarbon material that prohibit offshore dumping, the slurry may be formed at a desired NORM to liquid ratio and thereafter further processed to separate the hydrocarbon phase from the slurry or solid phase, and if present, a separate water or aqueous phase . The further hydrocarbon separation may be carried out using any suitable technique such as processing equipment made available from CET-CO of Australia. Once treated for hydrocarbon separation, the slurry may then be disposed as stipulated by regulatory authorities .

The third disposal technique involves mixing the slurry with the minimum amount of water and thereafter pumping the slurry into an abandoned well and capping the well with a concrete capping. If desired, the slurry can be drawn by a venturi action into the well with the concrete material .

Figures 2, 3 and 4 illustrate an example of a plant that embodies the process described above. The plant is capable of being housed in a conventional shipping container 30, suitably 5400mm in length and therefore, can be easily transported via ship, rail, or truck and trailer . As can be seen in Figure 2 , shipping containers of this length are available in two halves , namely and upper half and lower half. The lower half of the container 30 is shown in Figure 2 , and the upper half of the container is simply fitted in position on the lower half using a crane for transportation.

The plant is supported on a base 31 which has at least four corner ballards 32a, 32b, 32c, 32d to fend off equipment items and prevent against damage during lowering of the plant into a shipping container 30. The ballards

32a, 32b, 32c, 32d may also provide attachment points for a crane to raise and lower the plant.

The plant includes a feed assembly comprising a lifting mechanism 33 for lifting, tipping and emptying storage containers of scale material onto a sloped table 34. The lift mechanism may have any suitable drive including hydraulic, rack and pinion or gearing system for lifting and empting the storage containers 10. The feed assembly also includes a retractable roller conveyor 35 for moving the storage containers 10 into and out of engagement with the lifting mechanism 33.

Scale material emptied onto the table 34 slides along the table 34 and onto the fine screen separator 11 having an aperture size of 2 mm. Arranged below the fine screen separator 11 is a water spray 12 for spraying fine particles falling through the screen 11. The chute 13 directs water and the fine particles entrained therein into the mixing vessel 14. On the outlet side of the fine screen separator 11 is a further sloped table 14 which conveys the scale material to the coarse screen separator 15. The coarse screen 15 has an aperture of 50mm and particles falling through the screen 15 fall directly into the inlet 18 of the wet milling machine 16. Coarse particles held on the coarse screen 15 may be manually broken by an operator using a hammer so that they fall through the screen 15 and into the milling machine 16 with the remainder of the scale material. It will be appreciated that the coarse material held on the coarse screen 15 may be crushed via any suitable means including automated rollers, hammers and alike. The milling machine

16 is operated so to produce a particle size of 2mm or less. In one embodiment, the particles have a distribution in 90% is less that 0.5mm in diameter. The ground particles are then fed to the mixing vessel 14 and mixed with water. A water supply system comprising piping, pumps and liquid valves control the rate at which: i) water is discharged from the water spray 12; ii) fed to the coarse screen 15 and in turn, the milling machine 14; and iii) the mixing vessel. The water supply system also comprises a water tank that may be located on the plant base, or optionally remotely located and connected to piping of the plant via quick acting couplings 36. Slurry material discharged from the mixing vessel 14 is piped via a quick acting coupling 37 to a waiting storage tank, or alike via a hose or piping coupled thereto.

An operator control panel 41 may be located in an electrical cabinet. In additional, control buttons for operating the lifting mechanism 33, vibrations of the fines screen separator 11, milling machine 16, mixing vessel agitator 14, liquid pumps and valves, and/or emergency stop buttons may also be distributed over the plant as desired or located on the control panel 41.

Additional features that facilitate use of the plant include :

• retractable or removable overhead shade cloth 38 to shade operators while at work;

• retractable or removable overhead rain covers 39;

• retractable or removable side steps to allow easy access onto and off the base; and

• retractable or removable safety guards about the lift mechanism 40.

Those skilled in the art of the present invention will appreciate that many variations and modifications may be made to the preferred embodiment of the invention described above without departing from the spirit and scope of the invention.

Claims

1. A process of treating scale material containing naturally occurring radioactive material, the process including the steps of: a) grinding the scale material to form particulate material having a particle size of less than 10mm diameter; and b) forming a slurry mixture containing the particulate material formed in step a) and liquid.

2. The process according to claim 1, wherein the process includes a fines separating step in which fine particles having a size up to 5mm are separated from the scale material to form a fine particles stream prior to the scale material being ground according to step a) .

3. The process according to claim 2, wherein the fine particles separated by the fines separation step have a size less than or equal to 2mm.

4. The process according to claim 2 or 3, wherein the fine particle stream is adding directly to the slurry mixture formed according to step b) .

5. The process according to any one of claims 2 to

4, wherein the fines separation step involves screening the scale material on a screen separator and spraying the fine particles that have passed through the screen with liquid.

6. The process according to any one of claims 1 to

5, wherein the process further includes a coarse separating step in which coarse particles having a size of at least 30 to 80 mm in diameter are separated from the scale material prior to the scale material being ground to step a) .

7. The process according to claim 6, wherein the coarse material separated in the coarse separation step is subjected to a pre-grinding step, in which the coarse particles are broken to a size of less than or equal to 30 to 80 mm diameter.

8. The process according to claim 7 , wherein the pre-grinding step include manually hammering the coarse material on the coarse separation screen having apertures of 30 to 80mm.

9. The process according to claim 7 or 8 , wherein the course material ground according to the pre-grinding step is then returned to the scale material and subjected to grinding according to step a) .

10. The process according to any one of claims 1 to

9, wherein step a) includes wet milling the scale material .

11. The process according to any one of claims 1 to

10, wherein step a) includes grinding the material to a particle size of equal to or less than 5mm.

12. The process according to any one of claims 1 to 10, wherein step a) involves grinding the scale material to a particle size range in which 90% of the material is grounded to less than 0.5mm.

13. The process according to any one of claims 1 to 12 , wherein when the scale material includes residual hydrocarbon materials the process further includes separating the slurry formed according to step b) into the following phases:

(i) a hydrocarbon or hydrophobic phase, and (ii) an aqueous phase containing the particulate material for disposal thereof.

14. The process according to any one of claims 1 to 13, wherein step b) includes forming a slurry having a radioactive activity of less than 1 becquerel (Bq) per gram.

15. The process according to any one of claims 1 to 13, wherein the slurry formed according to step b) has a minimum amount of the liquid possible for a flowable material and has a total solid mass to liquid ratio in the range of 1 - 2 : 1.

16. The process according to claim 15, wherein the process includes feeding the slurry into the well bore and thereafter capping the well bore with concrete.

17. The process according to any one of claims 1 to 16, wherein the scale material includes any one or a combination of the following naturally occurring radioactive material: radium 226, radium 228, radon 222, uranium and thorium and any daughter elements thereof.

18. A plant that treats scale material containing naturally occurring radioactive material , the plant including : a grinding machine that breaks scale material to a particle size of less than 10mm diameter; and a mixing vessel in which the scale material from the grinding machine is mixed with liquid to form a slurry.

19. The plant according to claim 18, wherein the plant includes a fines separator having screen or sieve apertures of 5mm, the fines separator is located upstream of the grinding machine so that the fines separator separates fine particles from the scale material and holds scale material on the screen to be fed to the grinding machine .

20. The plant according to claim 19, wherein the fines separator has apertures of approximately 2mm.

21. The plant according to claim 19 or 20, wherein the plant includes a channel or chute located at an underside of the fines separator screen, and one or more than one outlet that discharges liquid to wash the fine particles that have passed through the fines separator screen into the mixing vessel.

22. The plant according to any one of claims 19 to 21, wherein the plant also includes a coarse separator having screen or sieve apertures of a size in the range of 30 to 80mm, the coarse separator separates coarse material from the scale material prior to the scale material being fed to the grinding machine .

23. The plant according to claim 22 , wherein the coarse separator has a screen on which coarse material held thereon can be crushed so as to pass through the apertures of the coarse separator and, in turn, be treated with the scale material in the grinding machine.

24. The plant according to any one of claims 18 to 23 including a lifting mechanism that is adapted for lifting and emptying containers in which the scale material is stored for treatment by the grinding machine.

25. The plant according to any one of claims 18 to 24, wherein the grinding machine breaks the scale material to a particle size of equal to or less than 5mm.

26. The pant according to any one of claims 18 to 24, wherein the grinding machine breaks the scale material to a particle size range such that 90% of the material is ground to less than 0.5mm.

27. The plant according to claim 21 or 22, wherein the plant includes a liquid distribution system that supplies fresh water or sea water to the mixing vessel and/or the outlet beneath the fines screen separator and/or the coarse screen separator and/or the milling machine .

28. The plant according to any one of claims 18 to 27, wherein the plant includes a base on which the plant is supported, the base capable of being housed in a shipping container or a lower half thereof for transporting the plant.

29. A transportable plant that can be housed inside a shipping container, the transportable plant including: a base on which the plant is supported so that the plant can be moved in and out of a shipper container by moving the base; a grinding or milling apparatus breaking scale material to a particle size of less than 10mm diameter; and a mixing vessel in which the scale material from the grinding or milling apparatus is mixed with liquid to form a slurry.

30. The transportable plant of claim 29 including any one of the features of the plant according to claims 18 to 27.