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By A. K. Bakshi

Mineral suspensions show Newtonian flow properties at lower solid concentration, but change into non-Newtonian regime as the solids content is increased. For Newtonian fluids viscosity is independent of shear rate, but for non-Newtonian fluids it varies with rate of shear. Therefore, measurement of viscosity at a shear rate, different from the process will be futile unless the slurry is Newtonian. This is especially true for hydrocyclone operation, where the rate of shear is different at different points within the hydrocyclone. In this case, it is very important to determine the flow type of the suspension before attempting to establish any correlation between viscosity and process efficiency. A new technique to distinguish such changes in flow type has been developed. This involved a co-axial cylinder type viscometer which measured apparent viscosity at a low shear rate, and a vibrating sphere type viscometer which measured the apparent viscosity at a high shear rate. Special precautions were taken to allow measurements of viscosity of rapidly settling mineral suspensions. Because the vibrating sphere viscometer operated at a much higher shear rate than the rotating viscometer, the two instruments together could determine the shear-rate dependency of the viscosity. Ground silica of 80% passing 65~m size in water was used to prepare slurries at concentrations ranging from 1O-70wt% solids. Viscosity of each slurry sample was measured simultaneously by both the viscometers and the results were compared with each other. With this technique, it was found that all the silica slurry samples were in the Newtonian flow regime.

Jan 1, 1995

By T. L. Carstensen

The Miami In-situ mine of BHP Copper is located in Globe-Miami, Arizona. The mine leaches mineralized leach capping over a supergene enriched sulfide deposit, and has produced over 500 million lbs of copper during the last 50 years. The Miami unit has identified several opportunities to enhance and expand in-situ production. A computer block model consisting of strict geologic controls, mineralogy, and metallurgical data was developed to assist in the determination of the leachable copper resource. An understanding of the accessibility and solubility of the resource to leaching solutions and the integration of hydrogeologic and hydrometallurgical information was necessary for completion of this project.

Jan 1, 1997

By Donald Crowell

Due to falling metal prices and depletion of ore reserves, lead-zinc mining in the Leadville, Colorado, area gradually came to a halt in the 1950's. Exploration work continued, however, and by 1969 sufficient ore had been blocked out to warrant sinking a shaft and erecting a new concentrator to treat 700 tpd. The new shaft and concentrator were to be located in Iowa Gulch several miles east of Leadville at an elevation of 11,100 ft. The Leadville project is a joint venture between Newmont Mining Company and ASARCO with ASARCO being the operator. Design work began in the fall of 1969. Engineering was done by Torkelson Engineering Company of Salt Lake City in conjunction with the Central Engineering Department of ASARCO. The plant was constructed by Stearns-Roger Corporation. Construction began in the spring of 1970 and the plant went onstream in April, 1971. Flow sheets and equipment lists are attached. This paper will describe the flow sheet very briefly and discuss in more detail those aspects of the design which may be of interest, particularly the provisions for expanding the capacity of the plant.

Jan 1, 1972

By Arthur W. Ruff

The iron-ore beneficiation and shiploading facilities of the Marcona Mining Company are at San Nicolas Bay which is on the Peruvian coastal desert about two hundred and seventy miles south of Lima. The mines are at elevation of 2,500 ft. Crude ore is transported from the Mine primary crushers to the beneficiation plants by ten miles of overland belt conveyors. After the predominantly magnetic ore is reduced to minus 3/4 in. in the secondary crushing plant, the ore is ground by rod and ball mills and concentrated with magnetic separators. The concentrate slurry is pumped to a thickening and filtering installation for desliming and dewatering. Pelletizing is accomplished with a Lurgi and also a Dravo-Lurgi machine. Deep-water shiploading facilities are available close to the beneficiation plants. Figure 1 shows a flowsheet of the general operation. Pelletizing operations are scheduled 24 hours a day and 365 days per year. A maximum tonnage rate with a high percentage of operating time is necessary to produce the three and one half million tons per year required from the two pellet lines. Process control is a major responsibility and of primary concern to all Operating personnel. The particle size, moisture, and chemical composition of the filter cake must be closely controlled to get uniform high-grade pellets. Key points are sampled routinely and analyzed on a two-hour basis to provide the necessary structure and chemical data to maintain a superior final product. The iron content of the pellets is held between 65.3 and 65.8 percent with 4.0 percent Si02. Sulfur is below 0.04 percent and copper is below 0.02 percent in the finished pellet.

Jan 1, 1968

By E. O. Strahl

In the search for economic mineral deposits, the need for efficient mineral or chemical assays is of prime importance. Costly analytical methods and long delays in obtaining assay results severely limit the effectiveness of an exploration program. The assay problem becomes acute once a potential ore body is located and large numbers of samples are generated in close interval drilling programs. In order to avoid the delays and high costs of extensive assays, the exploration geologist or mining engineer is likely to be required to curtail his drilling program, composite samples, or restrict the required analyses to a limited number of critical elements. As a result, the definition of the potential ore body may be less than needed for final economic evaluation. The assay requirements for bauxite exploration usually involve a considerable number of total elemental and empirical analysis. Since the Bayer process for extracting alumina from bauxite involves the selective dissolution and reaction of specific minerals from the bauxite, a direct chemical analysis for elemental composition yields only a portion of the data required to effectively describe the potential economic value of ore body or deposit. To fully characterize the economic value of a bauxite requires digestion, mud separation and mud settling tests under conditions approximating a commercial Bayer plant. A close approximation of the process behavior of a bauxite also can be calculated from a combination of the chemical and mineralogical analyses. By determining the elemental chemistry, mineralogy, and Bayer plant processing characteristics of a few samples of a given bauxite, correlations can be derived that permit defining a bauxite in terms of a given set of process conditions.

Jan 1, 1977

By T. F. Torries

The primary merit criteria used by the mining industry is internal rate of return (IRR) rather than net present value (NPV) although NPV is favored by academicians. This paper discusses the problems with IRR and NPV and compares the multi-goal nature of decision makers and their need for information with the characteristics of NPV and IRR. Conclusions are that both NPV and IRR are needed for investment ranking, that NPV suffers the same multiple root problem as does IR.R, and the determination of incremental IRR to reach NPV consistent project ranking is misguided in practice.

Jan 1, 1997

By Fredy A. Elorrieta Agramonte, Gabriel von Rickenbach, Roberto Luis Fonseca, David Córdova Rojas, Rolando Romero, Rico Brändle

The mine’s economic life is dynamic by nature. Some factors that create this scenario are the need to recognize new exploitation areas, the evolution of the mineral prices and the development of new technologies to access them. The dynamics of mining development, especially in the underground environment, changes significantly as the stages unfold. In many cases the final solution differs greatly with the initial. The frequent presence of new conditions and factors often cause the mine to develop in a quasi-permanent transition stage, which could be characterized by the generation of dynamic micro-seismic events that could cause rockburst damage in some specific areas. Although they may be infrequent, these dynamic events can have an important adverse impact on mine safety and causes serious losses. Also, changes in the production schedule during exploitation could be a big issue if the problem is not effectively addressed. When the transition of the mine to an active micro-seismic environment begins as an unforeseen scenario, it is frequent to use static ground support systems as they are readily available. Traditionally, the support systems used are reinforced shotcrete with a middle layer of Welded Standard Wire Mesh (WSWM) and Chain Link Standard Wire Mesh (CSWM) of reduced gauges, i.e. wires less or equal than 4 mm in diameter. Although, this support system is used to control static instability problems, there is no good reference of its energy absorption capacity under dynamic load conditions, creating uncertainty in the effectiveness of controlling rockburst events. These support systems are analyzed at the present paper, testing the reinforced shotcrete layer with 4 mm diameter of WSWM and CSWN under dynamic load. Additionally, the influence of the use of high tensile strength steel wire in the meshes (HSWM) compared to the previous ones, is analyzed to assess the scope in controlling rockburst events and keeping the safety of underground environment.

Apr 26, 2022

By J. Kretschmann, P. Goerke-Mallet, C. Melchers

Mining always leaves a mark behind. Dealing with this legacy is not only a tremendous challenge in Germany, but internationally too. The Technical University Georg Agricola (THGA) in Bochum, Germany, has established a Research Center for Post-Mining. Researchers combine expertise from a variety of technical and nontechnical fields in their quest to shape the post-mining era that completes the mine life cycle. In this respect, the Research Center focuses on four research areas: Perpetual tasks and mine water management, Geomonitoring, Material sciences and site transition. With more than 200 years of successful partnership with the mining industry in Germany and abroad, THGA offers a perfect setting for fresh and sound ideas in order support mining’s social license to operate. The aim of the paper is to describe the Post-Mining Research Center along with exemplary research projects that are of interest to the mining industry globally and to foster technical communication and research networking.

Mar 2, 2022

By E. Fregeau-Wu

To recycle steelmaking slags for their iron, manganese, and lime contents, removal of the phosphorus-bearing dicalcium silicate and calcium phosphate is essential. Slow-cooling of slags was necessary to promote the sufficient grain growth to achieve liberation. In-situ grain size distribution determination showed that a high soaking temperature, a long soaking time, a very slow cooling rate, and the addition of fluorspar were shown to promote grain growth. High gradient magnetic separation on slow-cooled slags removed much of the dicalcium silicate. Liberation modelling was used to discuss the breakage and beneficiation characteristics of the slow-cooled slags.

Jan 1, 1992

By R. E. Nivens

In the past, Newmont Gold Company relied on cement for their ore agglomeration process. With assistance from Betz Industrial, Newmont began Investigating the use of polymers for ore agglomeration. If gold recovery would not be jeopardized, then polymers could replace cement and possibly reduce operational costs associated with cement agglomeration. The following outlines the preliminary testing conducted to determine the feasibility of polymer agglomeration with Newmont's ore and the results of the test heap, which was constructed so the program could be examined under actual operating conditions. Similar polymer agglomeration testing has been successfully performed in other Nevada gold operations. By eliminating the need for cement, a polymeric agglomeration program could improve material handling operations, as well as offer the following additional savings. First, the polymer application uses only lime for adjusting basicity, the polymer does not contribute any alkalinity to the heap. Because lime is more soluble than cement, detoxification of the heap becomes much faster and less costly for the mine relative to rinsing cement alkalinity. The following graph compares the detoxification rate of cement and polymer over a 33 day cycle.

Jan 1, 1993

By Mustafa Akser

The Pipestone Lake anorthosite complex in Manitoba, Canada, was recently been re-identified as a potential source for titanium, iron, and vanadium. The present study utilized a 350 kg hard rock sample, which originated from the "Main Central" zone of the deposit. Commercial pilot-size equipment, such as dry low intensity roll magnets, wet high intensity magnets (WHIMS), and high tension electro-dynamic roll separators, was employed. As products, ilmenite up to 48.5% TiO2, and magnetite concentrates up to 87.9% Fe3O4 with 5.25% TiO2 were obtained. The majority of the vanadium reported to the magnetite concentrate. Subsequent characterization of various separation products shed light on the potential grade and recovery of the minerals from this deposit.

Jan 1, 1996

By S. Usui

In a previous article1 the methyl stretching vibrations for a series of xanthates and amines were reported, and the frequency of the methyl stretching vibrations in a homologous series of the alkyl compounds were shown to decrease exponentially with chain length and approach a limiting value corresponding to that of saturated hydrocarbon beyond six or seven carbons. These observations were explained quantitatively by the theory of Goto and Takenaka2 who proposed an equation relating the frequency shifts to the inductive effect of polar groups. As a result, the alkyl groups in the shorter chain heteropolar compounds were interpreted as becoming somewhat polar, and a good correlation was observed between the CH3-stretching frequencies and such surface chemistry parameters as contact angle, surface tension lowering, solubility, and critical micelle concentration" The substitution of fluorine atoms, the most electronegative of all atoms, for the hydrogen atoms in alkyl groups was expected to reverse the direction of the inductive effect within a heteropolar molecule, and its effect on the C-F stretching frequency shifts and on some surface chemical properties became of interest. In a recent study the C-F stretching frequencies of a series of normal perfluorocarboxylic acids and a few 1,1' -dihydroperfluoro alcohols were determined as a function of chain length and the results were compared with the corresponding hydrocarbon analogs. Furthermore, the nature of the induced polarity in the hydrocarbon and fluorocarbon groups was investigated through surface potential measurements at the interfaces of air-aqueous solutions of normal butyl alcohol and of l,l'-dihydroperfluorobutyl alcohol and through differential capacity and electrocapillary measurements at the interfaces of mercury-aqueous solutions containing the above two alcohols. Experimental Normal perfluorocarboxylic acids and 1,1' -dihydroperfluoro alcohols were provided through the courtesy of the 3M Company, St. Paul, Minnesota. Normal butyl alcohol was purchased from Distillation Product Industries, Rochester, New York. A Perkin-Elmer Model 621 infrared spectrophotometer was used to investigate the spectra in the frequency region of 1200 to 1270 cm-l with frequency scale

Jan 1, 1971

By T. A. Doyle

Column and batch test methods are used to simulate and model the leaching of various mining by-products. Batch tests are simpler, while column tests more intuitively represent the field conditions to be simulated. Projects that have included different types of leaching tests illustrate the strengths, limitations, and associated uncertainties of each. Column and batch tests have been used to evaluate arsenic solubility in leachate from treated copper smelter flue dust, to simulate the leaching of pit wall rock from a proposed gold mine, and to simulate the release of uranium from aquifer materials.

Jan 1, 1998

By G. R. Giuliani

Hanna Mining Company's Groveland Mine is located in the Upper Peninsula of Michigan. The low grade iron ore deposit consists of a mixture of magnetite and hematite with chert, jasper, quartz and various iron silicates (1). The ore is beneficiated by magnetic separation and anionic flotation of the iron minerals with chemical depression of the silica. The magnetic concentrate makes up about 75% of the concentrate. The concentrate is pelletized at the rate of 2.0 million LTPY of pellet production. The concentrator facilities were started up in 1959 and the concentrate was marketed as sinter feed until 1963 when the concentrator was expanded and the pelletizing plant was added. The pellet plant now consists of regrinding, elutriation, filtering, balling and induration. The pellet machine is a straight grate which employs updraft drying and cooling and downdraft drying, preheat and firing. It is necessary to regrind the concentrate before pelletizing. The con-centrate is 60% passing 325 mesh, with a surface area of ±lOOO cm2/Gm, and must be ground to about 83% passing 325 mesh, 1600 cm2/Gm blaine surface area, for pelletizing. The energy for regrind has been reduced from 12.5 KW per LT to 8.80 KW ate of 2.0 million per LT. This was the result of changes made in the concentrator where originally a coarse spiral concentrate, instead of the magnetic concentrate which is screened on fine screens to reduce the coarse fraction and prevent overgrinding before flotation, was produced. Also in 1968 an additional concentrating line was added to the concentrator which employs more grinding power than the other three lines. The demand for a high iron grade and lower silica pellet resulted in the investigation of different schemes of upgrading the reground concentrate which had more iron values liberated during grinding for surface area. The reagentized material presented many problems, mainly in selectivity trying to flot the iron and with high reagent consumption having to dereagentize the concentrate for amine silica flotation, in the various flotation systems tried. Tests were then conducted with elutriation (2) which proved satisfactory by removing the lower specific gravity, fine gangue material from the heavier material with the

Jan 1, 1977

By S. Tuylu, D. Adiguzel, A. Bascetin

"In recent years the fact that mining tailings cause serious environmental problems resulted in increasing number of studies about their disposal, storage and usability in various areas. Therefore the new studies about using the tailings for some purposes such as using in shotcrete or producing concrete have been increasing recently. The study is focused on applicability of tailings for producing shotcrete. Under this scope it is considered that mining tailings can bring many advantages in case of that they are used instead of sand, silt or fine aggregate in shotcrete applications. Most important advantages can be listed as decreasing shotcrete cost, decreasing amount if mining tailings to be disposed and the contribution to be provided on sustainable production of sources. The main objective of this study is the investigation of using mine tailing instead of fine aggregate in shotcrete. In this study, 10 shotcrete designs in different proportions were formed, and properties of the mixtures were identified. Then, the experimental results were statistically analyzed, the effects of the amount of the tailing material used on shotcrete properties were presented, and empirical approaches that can be used for the estimation of these properties were developed. INTRODUCTION The disposal of high amount mine tailing on the surface is caused a lot of problems in terms of environmental impact. Unfortunately, it is known that classic disposal techniques such as tailing dam cannot provide a solution these problems. The tailing dams which are usually used in the disposal of mining tailings bring along many problems in terms of cost, environment, and human health. So mine tailings are used in different production such as shotcrete. This technique is becoming increasingly common during recent years. The usability of mine tailings in brick and concrete production instead of cement and fine aggregate has been studied by many studies [1-4]. This situation has been promising for the usability of tailings in shotcrete which is commonly used for ground support especially in tunnels. Shotcrete (sprayed concrete) is applied mainly for construction of tunnels, shafts, renovation works and strengthening of slopes. Main advantage of shotcrete is fast development of strength, which quickly ensures stability of strengthened structure [5]. Shotcrete can be defined as spraying the grout consisting of water, aggregate, cement and optional additive mixture on the desired surface with a compressed air. According to the definition of the American Concrete Institute (ACI), it is the spraying of sprayed grout or concrete on a surface at high speed with air pressure [6]. In recent years, the use of shotcrete for the support of underground excavations is decreased in the mining industry. The design of shotcrete support for underground excavations is a very imprecise process. Strength and pumpability properties of shotcrete are very significant for determining suitable shotcrete design. Flow characteristics of the shotcrete must be determined for pumpability and fluidity of the material."

Jan 1, 2017

By James R. Garvey

The impact of conversion on the coal industry can be summarized very briefly: We are going to have to mine an awful lot of coal. Fortunately, the United States has the coal reserves available, and given the right conditions, we can mine it. The coal reserves of the United States are enormous. If we consider them on the basis of proved reserves, using the standards of the petroleum industry--that is, resources mapped and explored and recoverable with present techniques at close to present costs--and compare that with the reserves of other fuels, coal constitutes 88 per cent of the proved recoverable energy resources of the nation. That includes oil, natural gas, oil shale and uranium, so long as the uranium is used in burner reactors. If we consider resources on the basis of "ultimate recoverable" reserves, that is, those resources which can be extracted with improved technology and at somewhat higher costs--and if we include those resources of all fuels not yet found but believed to be waiting discovery--coal still accounts for 74 per cent of the national total. We have built a hydrocarbon economy in which about 76 per cent of our total energy needs are supplied by petroleum and natural gas, and about 20 per cent by coal. Domestic resources of oil and gas are running dangerously low and, assuming a continued hydrocarbon economy, the 20 per cent supplied by coal may increase dramatically. We already import nearly a quarter of the petroleum we consume, and the chief source of additional imports seems to lie in the politically unstable Middle East. Natural gas is in even shorter supply, and the problems of importing it seem at least as difficult as those of oil. The fact is, the United States is already relying to an increasing extent on foreign fuel sources. There is an obvious national risk in making an important part of energy supply hostage to foreign governments of uncertain tenure and friendliness. There is also an economic risk--one of the chief reasons for last year's economic freeze was to try to correct the deficit in our balance of payments; it is obvious

Jan 1, 1972

By Patrick Shea

Old mine workings are found throughout the Western United Sates on lands administered by the U.S. Bureau of Land Management, U.S. Forest Service and private lands. Some of these mine workings date back to the late 1800s. There may be as many as 100,000 sites on lands administered by the National Park Service, U.S. Forest Service and Bureau of Land Management. The U.S. Department of the Interior has worked with the U.S. Geological Survey, the U.S. Forest Service, the U.S. Environmental Protection Agency, and western state governments to identify and prioritize these sites on Bureau of Land Management, National Park Service and U.S. Forest Service administered lands. This presentation will discuss the accomplishments we have made to date to clean up inactive and abandoned mine sites, focusing primarily on lands administered by the Bureau of Land Management.

Jan 1, 2000

By B. Mather

Discussion by B. Mather I was very glad to see an article on alkali-silica reactivity of concrete aggregate in Mining Engineering. It is a topic that should be reexamined every 45 or 50 years. The last paper (that I am aware of) that examined this topic in Mining Engineering was Rexford (1950), who, at the time, was chief of the Petrography Section, South Pacific Division Laboratory, Corps of Engineers, Los Angeles, CA. The paper was presented at the AIME meeting in Los Angeles in October 1948. Professor Leming's discussion generally reflects the current state-of-the-art; but it provides no references for more detailed information. I wrote a paper titled "How to avoid excessive expansion of concrete due to alkali-aggregate reaction," which was included in the Proceedings of the Second International Conference on Alkali-Aggregate Reactions in Hydroelectric Plants and Dams (Mather, 1995). In it, I emphasized that it was the hydroxide ion (not the alkali ion) that caused the pore fluid in the concrete to dissolve reactive silica, producing alkali-silica gel capable of taking up water, thereby, causing swelling and rupturing of the concrete. Excessive expansion will not occur unless there is a sufficient amount of potentially expansive alkali-silica reaction product and water. However, this will not occur unless there is a sufficient quantity of reactive aggregate and unless there is a mechanism by which the pH of the pore fluid can get well above the normal value of about 12.6. In many cases it is sufficient that the cementitious medium not only contains portland cement but also contains ground granulated blast-furnace slag (GGBFS) or a pozzolan such as fly ash, silica fume, metakaolin, volcanic glass or calcined shale - any of which may have been included for economic reasons. If, however, the person selecting the ingredients for concrete knows that the aggregate is reactive (with no alternate nonreactive aggregate available) and if the person knows that the only available portland cement has a high alkali content (i.e., more than 0.6% Na2Oe; Na2Oe = % Na2O + 0.658 x % K20), then it becomes irresponsible not to establish what reasonable precaution one should take. Professor Leming suggests using one of the following: 30% Class F fly ash, 50% GGBFS or 7% to 10% silica fume. My view is that one should prepare test specimens with the cement and aggregate to be used and then expose these both with and without at least two dosages of each of the various alternative materials (slag, pozzolan and lithium salts), so that the required dosage to control the expansion is established. Then, economic considerations can dictate the final selection. I would point out to the author that GGBFS is not a pozzolan and is not an admixture, but, rather, it is a latent hydraulic cement. An admixture is, by definition, a material other than hydraulic cement. I commend him for suggesting that aggregate producers should become more active in knowing about the reactivity of their products and the precautions needed to permit those products to be safely used in concrete. ? References Mather, B., 1995. "How to avoid excessive expansion of concrete due to alkali-aggregate reaction," Proceedings, Second International Conference on Alkali-Aggregate Reactions in Hydroelectric Plants and Dams, US Committee on Large Dams, Denver, CO, pp. 421-439. Rexford, E.P, 1950, "Some factors in the selection and testing of concrete aggregates for large structures," Mining Engineering, Trans. AIME, Vol. 187, pp. 395-402. Reply by M.L. Lerning Mr. Mather has once again provided a cogent and useful discussion. I am grateful to him for bringing these issues to my attention, as well as to the readers, and I am grateful for his discussion of several important factors in alkali-silica reactivity. Mr. Mather's discussion of the mechanism of alkali-silica reactivity (ASR) notes the critical role of the hydroxide ion. While the alkali hydroxides are highly soluble (reducing the solubility of the other primary hydroxide in pore solution, i.e., calcium hydroxide, and providing hydroxide ions that initiate alkali-silica reactivity), it is, as Mr. Mather quite correctly notes, the hydroxide ion that attacks the silica structure. This point was not clearly stated in my original article. As noted in the text, the requirements for mineral admixtures to mitigate or control ASR vary widely depending on the specific characteristics of the materials

Jan 1, 1998

By Anil K. Ray

Roof falls are one of the greatest hazards in underground coal mines worldwide. Due to stringent safety measures and extensive support system development, roof falls have been reduced significantly but they still persist in many underground coal mines. Some of the roof falls initiate with cutter roof or guttering. In the past, many factors have been identified as being responsible for the development of cutters and roof fall. These responsible factors can be broadly classified as stress related or non-stress related. In this paper the finer details of mining technique have been taken into consideration for better understanding of cutter roof and roof fall problems. Three dimensional finite difference modeling has been used to explain the mechanism of cutter development. Strain softening material behavior has been used to realistically simulate the cutter formation, and common cutting sequences as implemented in the field have been simulated. This was done with an objective to determine whether the cutting sequence has really any significant control over cutter formation or not. In addition to cutting sequences, the effect of cut length is also studied. The effect of step cutting and turning of crosscut into and away from major and minor horizontal stresses is also examined to see its influence on cutter development.

Jan 1, 2009

By V. Steinbach

Non-renewable mineral raw materials are grouped into three categories to investigate ways leading to sustainable use of natural resources: 1.) metallic resources, 2.) non-metallic resources with the exception of the fertilizer minerals, and 3) the fertilizer minerals for the nutrients nitrogen (N), potassium (K), and phosphorous (P). With the exception of minerals in Group 3 which are essential for plant growth, mankind does not need raw materials as such, only the intrinsic property of a material that fulfils a useful function. This is especially true for non-metallic materials. Metallic resources have the best chance to become renewable if one makes optimal use of the resources of the man-made technosphere. For the fertilizer elements K and N there does not exist a problem, because sea water or air respectively provide an inexhaustible source for them. This does not apply to P however. So P is serving as one of our apposite case studies for solving sustainability challenges. For all the challenges along the road from a non-sustainable to a sustainable resource economy technology can be envisioned to come to the rescue provided conditions that are considered to be essential for sustainable use for all natural resources-- affordable renewable energy and human ingenuity to find new solutions for functions, to optimize processes and to minimize losses-- are satisfied.

Jan 1, 2011