Claims:1. A method for beneficiation of iron ore slimes, the method comprising:
obtaining an iron ore slime comprising iron minerals including at least one of hematite, goethite, and magnetite along with aluminum gangue minerals consisting kaolinite and gibbsite, wherein the iron ore slimes contain 5-15% Alumina;
adding at least a portion of alkaline pH modifier to the iron ore slime to obtain a pH adjusted iron ore slime, wherein the pH of the iron ore slime is adjusted in a range of around 9 to 11.5;
conditioning the pH adjusted iron ore slime with a flocculation solution for causing selective flocculation of iron minerals and formation of floc containing iron minerals and tailings, the flocculation solution comprising Xanthan gum;
mixing the iron ore slime while adding the portion of the alkaline pH modifier and the flocculation solution, and allowing the floc to settle; and
separating the floc from the tailings.

2. The method as claimed in claim 1, wherein concentration of the Xanthan gum in the iron ore slime is in a range of 100 – 2000 gram per ton of solids.

3. The method as claimed in claim 1, wherein concentration of the iron ore slime is in a range of 45-61% Fe and 5-15% alumina and pulp density in the range of 1-15 weight% of solids.

4. The method as claimed in claim 1, wherein the pH of the iron ore slimes to be beneficiated is adjusted to 10.5.

5. The method as claimed in claim 1, wherein the iron ore slurry is readjusted to pH ranging from about 9 to 11.5 if a change in previously adjusted pH is observed.

6. The method as claimed in claim 1, wherein addition of the Xanthan gum as the flocculant facilitates in reducing yield of Alumina in the floc.

7. The method as claimed in claim 1, wherein addition of the Xanthan gum as the flocculant at pH 10 gives a yield of 49.4% with 62.4% Iron and 4.1% Alumina.

8. The method as claimed in claim 1, wherein addition of the Xanthan gum as the flocculant at pH 10.5 gives a yield of 49.6% with 65.2% Iron and 3.9% Alumina.

9. The method as claimed in claim 1, wherein addition of the Xanthan gum as the flocculant at pH 11 gives a yield of 51.4% with 66.2% iron and 3.7% Alumina.

10. The method as claimed in claim 1, further comprising allowing the iron ore slime to settle prior to separating the floc from the tailings.

11. The method as claimed in claim 10, wherein the iron ore slime is allowed to settle for a time varying between 5-60 minutes.
, Description:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
(See section 10 and rule 13)

Title of invention:
IRON ORE SLIME BENEFICIATION

Applicant:
Tata Consultancy Services Limited
A company Incorporated in India under the Companies Act, 1956
Having address:
Nirmal Building, 9th Floor,
Nariman Point, Mumbai 400021,
Maharashtra, India

The following specification particularly describes the invention and the manner in which it is to be performed.
CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY
[001] The present application is a patent of addition of Indian Patent No. 224/MUM/2012, filed on January 23rd, 2012, the entire content of which is hereby incorporated herein by way of reference.

TECHNICAL FIELD
[002] The embodiments herein generally relate to slurry treatment, and, more particularly, to a beneficiation of iron ore slimes using a slurry treatment system and method.

BACKGROUND
[003] Modern researches are focused on slurry beneficiation processes. Slurry beneficiation involves mineral processing in which gangue minerals are separated from ore to produce high grade material. Various methods allow to beneficiate grade slurry/ores. These methods involve processing of raw slurry in large apparatuses that can be installed at plant site. Examples of methods employed for beneficiation of iron-ore slimes includes magnetic separation, flotation, selective dispersion-flocculation, and so on.
[004] The typical methods utilized for beneficiation of iron-ore slimes results in production of low grade slimes/ores. With increase in demand for high-grade iron ore slimes/fines and limited availability of high-grade iron ore slimes/fines, the mining industry has no other choice but to utilize low-grade iron ore slimes/fines. Moreover, these low grade iron ore slimes/fines and tailings occupy land in the form of tailing ponds that are environmental hazards. In general, iron ore slimes/fines mainly consist of iron bearing minerals such as hematite and goethite as well as gangue minerals like gibbsite and kaolinite. The mining industry is facing challenges in processing the iron ore inundated with alumina that are present in the ore as the gangue minerals, since there are adverse effects associated therewith. Additionally, tailing ponds lock a large amount of land and pose an environmental hazard. Thus, the sustainability of iron and steel industry depends on find an industrially feasible solution to the upgrade slimes grade to blast furnace grade.

SUMMARY
[005] The following presents a simplified summary of some embodiments of the disclosure in order to provide a basic understanding of the embodiments. This summary is not an extensive overview of the embodiments. It is not intended to identify key/critical elements of the embodiments or to delineate the scope of the embodiments. Its sole purpose is to present some embodiments in a simplified form as a prelude to the more detailed description that is presented below.
[006] In view of the foregoing, embodiment herein provides a method for beneficiation of iron-ore slime. The method includes obtaining a sample of iron ore slime, and adding at least a portion of alkaline pH modifier to the iron ore slime for adjusting pH of the iron ore slime. Further, a flocculation solution is added to the iron ore slime for causing selective flocculation of iron minerals formation of floc containing iron minerals and tailings. The iron ore slime is mixed during adding of the alkaline pH modifier and flocculation solution, and the floc is allowed to settle, and the floc is separated from the tailings. The disclosed method is characterized in that the flocculation solution includes Xanthan gum, and addition of the Xanthan gum as the flocculation solution facilitates in enhancing yield of Iron in the floc.

BRIEF DESCRIPTION OF THE FIGURES
[007] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and modules.
[008] FIG. 1 is a schematic diagram illustrating process for beneficiating iron ore slimes/fines, in accordance with an example embodiment.
[009] FIG. 2 is a flow diagram illustrating a method for beneficiating iron ore slimes, in accordance with an example embodiment.
[0010] FIGS. 3A, 3B and 3C illustrate plots of % yield, % Fe and % Alumina plotted with pulp density of 5g/100 ml of slurry, in accordance with an example embodiment.
[0011] FIGS. 4A, 4B and 4C illustrate plots of % yield, % Fe and % Alumina plotted with pulp density of 10g/100 ml of slurry, in accordance with an example embodiment.

DETAILED DESCRIPTION
[0012] Some embodiments of this invention, illustrating all its features, will now be discussed in detail. The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items.
[0013] It must also be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, the preferred systems and methods are now described.
[0014] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0015] Iron ore fines and slimes are generated during mining and washing of iron ores. These contain low Iron grade and high alumina content thus are being dumped as waste. These tailings occupy land in the form of tailing ponds and pose serious environmental hazards. With the increased demand of steel and rapid depletion of high grade ores, iron and steel industries currently are forced to look for the alternatives to utilize these low grade iron ores/slimes. Indian iron ore mainly consist of hematite, goethite, gibbsite and kaolinite. As per the Indian Bureau of Mines guidelines, iron ore tailings containing >45% Iron can be considered as a resource and should be utilized. The tailings that are being generated currently contain percentage of Iron as high as 60% but are not being utilized owing to high alumina contents. Researchers are aiming to achieve <45% Iron in tails while beneficiating the slimes (Tailings). In order to utilize these fines and slimes, effective separation of iron bearing minerals from aluminum minerals is required. The processes like selective flotation and flocculation can be successfully applied, however, one requires an appropriate reagent scheme for them.
[0016] The present disclosure provides a method for beneficiation of iron ore slimes by using Xanthan gum as a selective reagent for selectively flocculating iron minerals present in the natural iron ore slimes. Particularly, the embodiments disclose process for beneficiating of iron ore slimes and fines that exploits the mineral surface charge and the particle terminal velocity to achieve said beneficiation. As is understood, the charge associated with particles suspended in a liquid is called surface charge. Zeta potential is a measure of the magnitude of the electrostatic or charge repulsion/attraction between particles, and is one of the fundamental parameters known to affect stability. In the process disclosed herein, particles may have negative surface charge due to which particles repel each other. When a reagent is added, it adsorbs on to the minerals masking the surface charge and hence particles tend to come closer and form flocs. When the reagent is selective, flocs are formed with particular particles and hence the selectivity is observed. The flocs that are formed settle faster than the other particles. Bigger the particles greater the settling velocity (terminal velocity) which can be understood through Stoke’s law.
[0017] In preferred embodiments, iron ore slimes and fines are recovered by a selective flocculation method. Those skilled in the art may understand that the terms "beneficiate", "beneficiation", and "beneficiated" refer to an ore enrichment process in which the concentration of the desired mineral and/or metal in the ore increases as the process proceeds. The separation method utilizes pH of the iron ore slimes or fines as a parameter to achieve acceptable grades of iron ore without addition of any external reagents. The reagents here refer to dispersants, flocculants and the collectors.
[0018] As will be described later in the description, while practicing the embodiments disclosed herein, the results of experiments suggest that Xanthan gum can be used for the beneficiation of iron ore slimes and fines. During the experiments, a concentrate containing >66% Fe and < 4% Al2O3 with 51.2% yield are obtained from the slime sample assaying 59.5% Fe and 6.6% Al2O3.. The present iron ore sample is selectively beneficiated from certain gangue minerals, particularly, gibbsite and kaolinite minerals.
[0019] The iron ore slurry may be formed in various ways known to the person skilled in the art. The pH of the iron ore slurry is then adjusted to a desired pH range of about 9 to 11.5, and preferably at 10.5. The desired pH range may be obtained by adding a pH modifier (acid and base), namely and preferably sodium hydroxide and nitric acid. It shall however be understood that pH adjustment to obtain desired pH range may be accomplished using methods known to those skilled in the art. Upon beneficiation, the iron ore slurry is subjected to further processing by any beneficiation processes, such as batch process, semi-batch process and continuous process.
[0020] While aspects of described methods and systems for iron ore beneficiation can be implemented in any number of different systems, utility environments, and/or configurations, the embodiments are described in the context of the following exemplary system(s).
[0021] FIG. 1 illustrates a schematic for iron ore beneficiation, in accordance with an example embodiment. A sample of iron ore slime or an iron ore slurry (also referred to as slurry or pulp) is obtained. The iron ore slurry may include minerals such as hematite, goethite, gibbsite and kaolinite, quartz. In an example scenario, the concentration of said minerals in the feed containing iron ore slurry includes Hematite 51.2%, Goethite 31.7%, Gibbsite 7%, Kaolinite 9.7% and Quartz 0.2%. The aim of beneficiation is to recover Hematite and Goethite and discard Gibbsite, Kaolinite and Quartz, as much as possible.
[0022] The pulp density of the iron ore slurry may be controlled by addition or removal of water to the iron ore slurry. Addition of water decreases the density of iron ore slurry pulp. In an embodiment, the addition of water may be done in flow before or during the pH conditioning/pH adjustment. Also, removal of water increases the pulp density of the iron ore slurry. In an embodiment, the removal of water from the iron ore slurry can be performed by filtration. Herein, experiments conducted by maintaining the pulp density of the iron ore slurry as grams of solids present per 100 ml of the iron ore slurry. According to an exemplary embodiment, experiments conducted with pulp density of 5 grams per 100 ml of the iron ore slurry, and 10 grams per 100 ml of the iron ore slurry, and the results are presented further in the description below.
[0023] The pH of the iron ore slurry is adjusted by adding a portion of alkaline modifier to the slurry. Examples of alkaline modifiers may include, but are not limited, to NaOH, KOH, Sodium Carbonate, and so on. The pH conditioning of the iron ore slurry or slime sample is performed since during beneficiation, for a given dispersant–flocculent combination, an optimum pH has to be maintained for best separation and maximum recovery of iron ore from the iron ore slurry or slimes. In an embodiment, the pH is re-adjusted in range of from about 9-11.5, and preferably 11.5 if any change is observed. In an embodiment, the pH of the iron ore slurry may be controlled by controlling a flow of the pH conditioner to the iron ore slurry. The result of studying the effect of pH during beneficiation process is presented in Tables 1, 2 and 3.
[0024] A flocculation solution (or reagent solution or flocculation agent) is added to the iron ore slime for causing selective flocculation of iron minerals formation of floc containing iron minerals. The flocculation solution is utilized for treating the iron ore slurry. The flocculation solution facilitates in agglomerating particulates that can then settle from the iron ore slurry. The flocculation solution can be mixed with the iron ore slurry for the purpose of treating the iron ore slurry to form flocculants (or flocs), such as clay, claylike waste, metal oxide particulate wastes, and so on. The flocculation solution includes Xanthan gum. Xanthan gum is produced by aerobic fermentation of sugar such as glucose, sucrose, or lactose by bacteria called Xanthomonas campestris. The bacteria can be isolated and grown on whey which is waste of cheese production. Xanthan gum is produced on commercial scale by a batch fermentation process. Downstream process includes the steps of- thermal treatment, cells removal, recovery with alcohol (normally ethanol), drying and milling of the gum. The global production of Xanthan gum is mainly concentrated in the United States, China, Japan, Netherlands. The addition of the Xanthan gum as the flocculation solution facilitates in enhancing yield of Iron in the floc. The result of adding Xanthan gum as the flocculation solution during beneficiation process is presented in Tables 1, 2, and 3.
[0025] Herein, the iron ore slurry is pH treated iron ore slurry. As previously discussed, for selective separation of iron ores, alkaline pH can be utilized. The mixture of pH treated iron ore slurry and flocculation solution is stirred and further allowed to settle. Particularly, the iron ore slime is stirred during adding of the alkaline pH modifier and flocculant solution, and the floc is allowed to settle. In one example, the mixing time for pH adjustment was taken as 15 minutes. In an embodiment, the iron ore slime is allowed to settle for a time varying between 5-60 minutes.
[0026] FIG. 2 flow-diagram of a method 200 for iron ore slime beneficiation, in accordance with an example embodiment. At 202, the method 200 includes obtaining an iron ore slime. The iron ore slime may be obtained from iron ore beneficiation plant. In an embodiment, concentration of the iron ore slime is in a range of 45-61% Fe and 5-15% alumina and pulp density in the range of 1-15 weight% of solids. At 204, the method 200 includes adding at least a portion of alkaline pH modifier to the iron ore slime for adjusting pH of the iron ore slime. Examples of alkaline pH modifier include, but are not limited to, NaOH, KOH, and so on.
[0027] At 206, a flocculation solution is added to the iron ore slime for causing selective flocculation of iron minerals formation of floc containing iron minerals and tailings. An important contribution of various embodiments described herein is that the flocculation solution includes Xanthan gum. In an embodiment, the concentration of the Xanthan gum in the iron ore slime is in a range of 100 – 2000 gram per ton of solids. The iron ore slime is mixed (stirred) during adding of the alkaline pH modifier and flocculation solution, and thereafter the floc is allowed to settle at 208. In an embodiment, the iron ore slime is allowed to settle prior to separating the floc from the tailings. In an example embodiment, the iron ore slime is allowed to settle for a time varying between 5-60 minutes. At 210, the floc is separated from the tailings. Herein, addition of the Xanthan gum as the flocculation solution facilitates in enhancing yield of Iron in the floc. Additionally, the addition of Xantham gum facilitates in reducing the yield of alumina in the floc. The variation of yields of iron and alumina in the iron ore slime with change in Xantham gum flocculation solution at different pH concentrations is described further by presenting various experimental results in Tables 1, 2 and 3 in the description below.
[0028] Referring now to Table 1, experimental results for iron ore slime beneficiation experiment using Xantham gum as flocculation solution at different pH concentrations is illustrated. For the purpose of present experiment, the Iron ore slime samples were obtained from iron ore beneficiation plants in Noamundi, Jharkhand, India and Barsua, Orissa, India.
[0029] In the present example, the iron ore sample is ground to below 400 mesh (i.e., <37 microns size) which is a typical size of natural slime sample. Sample assays 59.5% Fe, 6.6% Al2O3. The sample contains minerals hematite, goethite, gibbsite and kaolinite. The pH of the iron ore slurry is adjusted using sodium hydroxide. Xanthan gum is used as a flocculant (of flocculating agent).
[0030] Iron ore slurry sample of 10% pulp density is prepared by adding water to ground iron ore. 800ml of iron ore slurry was taken in beaker for each experiment. pH of the iron ore slurry then adjusted to desired value using sodium hydroxide. Xanthan gum (from stock solution) is added such that the Xanthan gum concentration in the iron ore slurry is 300 grams per ton of solids. The iron ore slurry is mixed using an impeller set up during pH adjustment and reagent/flocculating agent (xanthan gum) addition. Once reagent/flocculating agent conditioning is done for 3 minutes, the stirring is stopped to allow the flocs to settle. After 5 minutes of settling, concentrate (settled portion) is separated by decantation the supernatant, dried and analyzed for %Fe and %alumina using standard wet chemical analysis procedure.
[0031] The results of iron ore slime beneficiation experiments are presented in Table 1, below.

Table. 1
pH Yield, % Fe %Alumina
9 65.0 61.1 5.7
10 49.4 62.4 4.1
10.5 49.6 65.4 3.9
11.5 51.4 66.2 3.7

[0032] As is seen, Fe and alumina grade are improved with increasing pH of the iron ore slurry at same Xanthan gum dosage. A concentrate containing >66% Fe and < 4% Al2O3 with and yield of 51.2% is obtained from a slime sample assaying 59.5% Fe, 6.6% Al2O3. These results suggest that Xanthan gum is effective at high alkaline pH.
[0033] Another slime sample assaying 50.1% Fe and 8.0% Alumina, 6.9% loss on ignition (LOI) and 4.9% Silica was taken, selective flocculation experiments were performed at pulp densities of 5 and 10 grams of solids/100ml of iron ore slurry. Results are reported in Table 2 and Table 3 respectively. Effect of reagent/flocculating agent Xanthan Gum dosage and settling time are also studied at alkaline pH of 10.5.
[0034] Table 2. Results of selective flocculation experiments at pulp density of 5 grams of solids/ 100ml of iron ore slurry at alkaline pH of 10.5.
Xanthan Gum (g/t) Settling time (min) Sample
(Iron ore slurry) Weight% Fe Grade %Alumina %LOI %Silica
300 5 Concentrate 51.4 55.1 4.9 4.8 2.5
Tails 48.6 41.6 12.2 9.5 7.4
10 Concentrate 58.2 55.2 6.1 4.9 2.3
Tails 41.8 38.6 14.0 10.1 8.3
15 Concentrate 61.1 54.9 3.5 4.9 2.5
Tails 38.9 36.6 13.3 13.9 8.4
600 5 Concentrate 49.8 55.3 4.6 4.5 2.2
Tails 50.2 41.7 12.0 9.8 7.1
10 Concentrate 55.1 55.9 4.5 4.9 2.8
Tails 44.9 38.4 11.7 12.5 7.9
15 Concentrate 58.8 55.1 4.5 5.0 2.2
Tails 41.2 38.0 13.1 12.7 7.5
1000 5 Concentrate 47.0 61.4 4.6 5.1 2.2
Tails 53.0 45.1 5.7 9.4 7.0
10 Concentrate 54.3 59.3 4.7 5.1 2.1
Tails 45.7 43.6 12.2 10.2 7.6
15 Concentrate 57.4 59.0 4.7 4.6 2.2
Tails 42.6 41.4 12.7 11.0 7.8

[0035] Table 3. Results of selective flocculation experiments at pulp density of 10 grams of solids/100ml of iron ore slurry at alkaline pH of 10.5.
Xanthan Gum (g/t) Settling time (min) Sample
(Iron ore slurry) Weight % %Fe %Alumina %LOI %Silica
300 5 Concentrate 52.8 58.4 4.6 4.3 2.3
Tails 47.2 45.4 12.0 9.6 7.5
10 Concentrate 58.7 58.8 5.0 5.1 2.4
Tails 41.3 43.7 13.1 10.5 7.9
15 Concentrate 62.7 59.1 5.0 4.9 2.2
Tails 37.3 42.1 13.4 11.0 8.6
600 5 Concentrate 50.9 58.7 4.6 5.0 2.2
Tails 49.1 44.3 11.4 11.1 7.1
10 Concentrate 58.1 59.1 4.6 5.1 2.2
Tails 41.9 41.5 12.2 12.2 7.7
15 Concentrate 61.1 58.9 4.6 5.0 2.2
Tails 38.9 41.1 12.8 11.6 8.6
1000 5 Concentrate 50.1 59.9 4.4 4.8 2.1
Tails 49.9 42.5 11.5 10.8 7.1
10 Concentrate 57.7 59.2 4.5 4.6 2.3
Tails 42.3 43.1 12.5 11.4 8.9
15 Concentrate 58.0 60.1 4.6 5.0 2.1
Tails 42.0 41.4 13.2 10.8 7.5
[0036] Results from Tables 2 and 3 suggest the Xanthan gum improves the concentrate quality as high as 61.4% Fe. Interestingly, most of the tailings contain <45% Fe. Yield of concentrate is increasing with increasing settling time with consistent concentrate grades for settling time range being 5 – 15 minutes. Higher dosages of flocculating agent, for example 1000 g/t are required at lower pulp densities, and lower flocculant dosages, for example 300 g/t are sufficient for higher pulp densities i.e., 10 g/100ml of slurry.
[0037] Results of concentrate yield, Fe grade and % alumina are plotted for experiments with two different pulp densities i.e., 5 and 10 g/100 ml of slurry. Particularly, FIGS. 3A, 3B and 3C illustrates % yield, % Fe and % Alumina plotted with pulp density of 5g/100 ml of slurry, and FIGS. 4A, 4B and 4C illustrates % yield, % Fe and % Alumina plotted with pulp density of 10g/100 ml of slurry.
[0038] As is seen from FIGS. 3A-3C and 4A-4C, yield is observed to increase with respect to the settling time which is clear from the results of experiments with both pulp densities, 5g/100 ml and 10g/100 ml. Yield is increasing with lower Xanthan gum concentration. This is because the Xanthan gum is a viscosity modifier. Increase in concentration of Xanthan gum results in increasing the viscosity and decrease the settling rate. Increase in pulp density from 5 to 10 g /100 ml of slurry, has very small increment in yield for the all the experimental parameters variation.
[0039] Fe grade is increasing with increasing Xanthan gum content for pulp density of 5 g/100 ml of slurry. At pulp density of 10 g/100 ml of slurry, high Fe grades are achieved. Further increase in Xanthan gum concentration has not much effect on Fe grade. Settling time has also not shown any major change in Fe grades. % Alumina was observed to increase in the range of 3.5 to 6.1 %. For most of the experimental conditions it is around 4.6%.
[0040] Overall, increase in Xanthan gum concentration increases the Fe grade but decreases the yield. From these results, it is evident that experimental conditions can be selected based on the requirement of concentrate yield and grade.
[0041] Unlike the results of starch as explained in Indian Patent Application No. 224/MUM/2012, no incremental yields are achieved with increasing xanthan gum dosage. This is because xanthan gum is a viscosity modifier and increases viscosity even at low concentrations. The increase in viscosity leads to slower settling of flocs reducing the yields.
[0042] The present invention accomplishes the iron ore beneficiation without requiring addition of any external reagent-dispersant, flocculent or collector at any stage of the process, which eventually can reduce the burden of environment bemiring that has off late surfaced as one of the most formidable threat to iron ore processing industry.
[0043] The foregoing description of the specific implementations and embodiments will so fully reveal the general nature of the implementations and embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
[0044] The preceding description has been presented with reference to various embodiments. Persons having ordinary skill in the art and technology to which this application pertains will appreciate that alterations and changes in the described structures and methods of operation can be practiced without meaningfully departing from the principle, spirit and scope.