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By Sergey Gudkov, Yuri Yemelianov, Stanislav Balikov, Andrey Boldyrev, Andrey Bogorodsky

"The results of POX of refractory gold-bearing concentrates using halide-ion as a lixiviant for precious metals and activated carbon as an adsorbent are given. It was found that gold did not recover to the solution when halide was added during POX. Silver partially dissolved in the solution. When halide-based reagents and activated carbon were added during POX, gold dissolved and loaded onto the activated carbon. The degree of sulfides oxidation was 99.3-99.6%. The recovery of gold onto granulated carbon was 94.7-94.8% when using chlorine-bearing lixiviants: NaCL, CaCL and carnalite and 98-99% when using KJ and KBr. This treatment process of refractory gold-bearing concentrates combines sulfide oxidation, dissolution and adsorption of precious metals. The results of the metals recovery achieved using this process can be compared with the recovery during POX-cyanidation. In this case, sodium cyanide was not used. This allows the reduction of capital and operational costs due to the absence of cyanidation, CIL and detoxification of leaching tailings circuits."

Jan 1, 2014

By M. M. Fan

In Florida?s phosphate industrial practice, the most favorable upper size limit of froth flotation is 1.18 mm which corresponds to particle weight of about 2.8 mg. Conventional froth flotation is not efficient in upgrading coarse particles (+0.425-1.18 mm). A limited number of studies have been devoted to understanding and improving coarse particle flotation. We have shown that the coarse particle flotation performance can be significantly improved by the presence of picobubbles generated by hydrodynamic cavitation. In this study, the size of picobubbles produced under certain hydrodynamic conditions was measured by a laser particle size analyzer. A size-by-size flotation performance analysis of coarse phosphate froth flotation in the presence of picobubbles is conducted in terms of flotation kinetics, selectivity and recovery. It was found that picobubbles doubled the flota-tion rate, increased the P2O5 recovery more significantly for +0.85-1.18 mm particles than +0.425- 0.6 mm and +0.60-0.85 mm particles. At a given acid insolubles (A.I.) rejection, the presence of picobubbles increased the P2O5 recovery by up to about 25%.

Jan 1, 2014

By E. Vahidi

In this study, a hydrometallurgical treatment involving solvent extraction of zinc using D2EHPA (di-2-ethylhexyl phosphoric acid) has been investigated to recover zinc from an industrial zinc leach residue. The residue was leached with sulfuric acid producing leach liquor which was subjected to solvent extraction for enrichment of zinc and removal of impurities. Operating variables for the zinc extraction process, such as pH of the mixed solution (0.5~5.0), concentration of D2EHPA (5%~40%, w/w), temperature (25~60°?C), A/O volumetric phase ratio (1/2~4/1), concentration of tri-butyl phosphate (TBP) as modifier (3%~7%, w/w), concentration of NaR2RSOR4R in aqueous phase (0.05M, 0.1M, 0.2M) were also studied. Practically all zinc was extracted from the aqueous solution at pH 2.5 with 20% w/w D2EHPA in kerosene. At this operating condition, zinc could be extracted at one theoretical stage at A/O phase ratio of 1/1, as calculated by the McCabe-Thiele method.

Jan 1, 2014

By Kazutoshi Haga, Atsushi Shibayama, Altansukh Batnasan

"The aim of this study was to develop a hydromellurgical processing for removal of arsenic from high-arsenic copper sulfide ores and concentrates, providing increase in copper recovery. In this study, three different enargite ore samples containing 28.2–46.7% copper, 1.9–15.0% arsenic and 10.6–27.5% iron were used to determine optimum conditions for the extraction of copper and removal of arsenic. High pressure oxidative leaching process was preformed using various leaching reagents such as sulfuric acid (H2SO4), ferric sulfate (Fe2(SO4)3), hydrochloric acid (HCl), ferric chloride (FeCl3), sodium sulfate (Na2SO4), sodium chloride (NaCl) solutions and distilled water (DW), respectively, under the fixed conditions which were selected to be as follows: NaCl concentration, 0.34 M; concentrations of other leaching reagents, 0.1 M; particle size, -45 ?m; pulp density, 100 g/L; agitation speed, 750 rpm; leaching temperature, 160 ?C; leaching time, 60 min and total pressure (oxygen gas and vapor pressure) into an autoclave, 1 MPa. Results show that under the leaching conditions, more than 90% of copper leaching was achieved with lower than 2% arsenic content as a consequence of the formation of arsenic precipitates in a solution of Fe2(SO4)3–NaCl. It was determined that copper, arsenic and iron concentrations in the pregnant leach solution were 42 g/L, 0.3 g/L and 0.3 g/L, respectively. As a result, it can be concluded that the Fe2(SO4)3 solution in the presence of NaCl or FeCl3 are more efficient leaching media compared to other leaching agents under the high pressure oxidation conditions, because of their high copper recovery and lower arsenic level in the pregnant leach solution.INTRODUCTION Generally, copper is usually produced from copper sulfide ores by a combination of several processes which are flotation and smelting followed by refining [1-3]. Arsenic content in copper sulfide ores tends to increase due to the depletion of high grade copper deposits, hence conventional mineral processing and metallurgical processes cannot effectively treat these ores containing high levels of arsenic to obtain consistently high purity copper concentrates. Because high levels of arsenic in copper ores/flotation concentrates reduces the value of concentrates due to the restriction of smelting process and causes it to be a source of environmental pollution [4-6]. From this point of view, the known way of prevention against high-arsenic copper sulfide concentrates in further metallurgical treatments is to develop economically and environmentally competitive technologies for removal of arsenic impurity from copper sulfide ores before treating the ores/flotation concentrates by the pyrometallurgical routes."

Jan 1, 2018

By Ljudmil S. Grigorov, Eric Forssberg, Hanumantha Rao Kota, Robert J. Pugh, Lidia B. Alexandrova

"The effects of mixed collectors on some physicochemical parameters (thin film lifetime, kinetics of expansion of the three-phase contact, equilibrium three-phase contact angle and surface tension) involved in the elementary act of flotation were investigated experimentally.We have used the microscopic thin balance developed by Scheludko et al (1970) to study the stability and interactions within the thin film between the silica surface and air bubble with (i) a long chain C10 amine and (ii) a cationic/anionic surfactant systems consisting of mixtures of a long straight C10 chain amine with long straight chain C8, C10 and C12 sulfonates at 1:1 molar ratio. The experiments were performed at a range of concentrations at pH 6.5. The equilibrium contact angle was measured with a microscope technique using the modified Mingins-Sheludko method (Mingins and Scheludko, 1979). The surface tension was measured by the method of Wilhelmy (Adamson, 1960). It was found that the mixed surfactants caused lower contact angles, lower rates of the thin film rupture and longer film lifetime, compared to the pure amine system."

Jan 1, 2003

By I. V. Shadrunova

Annually it is formed more than 95 Mt of clinkers in iron and steel industry of Russia, including 79 Mt of clinkers in blast-furnace, steelmaking, foundry and ferroalloy productions. Complex development of clinkers will provide not only extraction of valuable components, but also preservation of ecosystems. Processing of solid slags is realized, as a rule, in a cold condition by mechanical methods only including stage-by-stage crushing of slag on devices, working on principles of compression and shift (jaw and roll crushers). However it doesn?t provide the complete extraction of metals from clinkers. The intensification of decomposition, in our opinion, can be provided under the use of the devices working on a principle of free kick. At such influence on a material, its destruction occurs on micro cracks, sides of cohesion that is there is a selective destruction of the components possessing various resistances to impact. Decomposition of a piece on the basis of free kick about a material or metal is realized in centrifugal-shock crushers and mills of research-and-production association ?Ural Center?. The share of the joints sharply lowering the efficiency of enrichment thus is minimal. The efficiency of application is proved by morph-metrical measurements with the help of system of image analysis ?SIAMS-600? and physical-mechanical tests of clinkers and their components (impact strength, micro hardness). The experience of application the devices of centrifugal-shock crushing for processing clinkers in blast-furnace, martin and converter productions of Open Society MMC, clinkers of rough-edged copper melt of Joint-Stock Company "Karabashmed" and aluminium clinkers of Joint-Stock Company « Samara plant of aluminium alloys » has allowed to confirm the efficiency of application these devices for selective decomposition of metallurgical clinkers and the opportunity of using clinkers as resource of ferrous and nonferrous metallurgy.

Jan 1, 2014

By C. L. Xiao

With reference to the test report carried out by Guangzhou Nonferrous Metal Research Institute in 1983, the mineral process flow sheet of Yichun Tantalum-niobium mine is determined based on the characters of ores and successful experiences in light of the problems in the existing flowsheet: The ore is desilted before crushing; the primary slime is separately treated; the staged grinding process used while the fine slime is collectedly treated with tantalum and niobium as the main recoveries and lepidolite and feldspar powder as the secondary. The flowsheet is featured by comprehensive recovery, low investment and low energy cost.

Jan 1, 2014

By R. J. Batterham

The science and practice of mineral processing has been driven for many years by the same set of challenges that shape the mining industry ? demand and supply, grades and their decline with time, mineralogy and the need to handle more complex ores, disposal and minimising of wastes and the availability of water, power, skilled labour and the like together with increasing expectations from the community, concerns on sustainability and safety and, as well, climate change forcing a more targeted approach on energy. In this paper, the author builds on previous reviews to the IMPC and suggests that while step changes are long overdue, the unprecedented demand mitigates against drastic changes. That said, the ?Mine of the Future? is already requiring some different approaches.

Jan 1, 2014

By Z. A. Zhou

In Canadian oil sands processing, flotation is used to recover liberated bitumen droplets from oil sands slurries. Similar to conventional mineral flotation practice, a fundamental limitation of recovering bitumen from low grade oil sand ores is its slow and ineffective aeration of the liberated small bitumen droplets. Gas nucleation and cavitation could provide better mechanisms for accelerating bitumen-bubble attachment. A research program was undertaken to examine factors affecting spontaneous bubble nucleation on bitumen surfaces. The results demonstrate that surface hydrophobicity and existence of gas nuclei in process water play a critical role for bubble nucleation. While there are more bubbles nucleated on highly hydrophobic silanated glass surfaces than on moderately hydrophobic bitumen, bubble nucleation on clean hydrophilic glass surfaces is negligible. Heating process water up to 85 ~ 95oC (as used in commercial operation) or boiling tap water prior to gas nucleation tests is shown to remove sufficient amount of gas nuclei existing in the water, thereby drastically reducing the number of bubbles nucleated on bitumen. Enhancing gas nuclei formation in hot process water is identified as a promising strategy to improve bitumen-bubble attachment during oil sands conditioning, and hence to increase bitumen recovery from low grade ores.

Jan 1, 2014

By L. S. Gertsch

The production of minerals for human use at locations other than the Earth is expected to ?advance ? human prosperity in ? ways that [do] not compromise the potential prosperity and quality of life of future generations? (Brundtland, 1987); in other words, sustainably. This paper examines the interaction of extra-terrestrial mineral production (ETMP) with the following sustainability imperatives: ? The sustainability of human activities on Earth; ? The sustainability of human activities elsewhere; ? Human survival in general, the ultimate sustainability goal. Some of the consequences of mineral production on Earth are widely considered to decrease the future prosperity and quality of human life. Examples include noxious by-products or wastes and unsettling economic up- and downswings. Moving mineral production activities to extra-terrestrial locations, where appropriate, will decrease many of its deleterious effects. Terrestrial mineral production presently is decreasing in some countries and increasing in others, moving from the cheaper and easier ores to more expensive, difficult materials. When the full costs of maintaining the terrestrial environment in a sustainable manner are included, total mineral pro-duction costs must increase. The cost of extracting mineral products from extra-terrestrial sources will be substantially higher, especially in the initial phases, but as the full costs of terrestrial production increase, at some point in the future (different points for different minerals), the curves will cross (Fig.1). This will occur at different points for different materials, a process whose prediction will be complicated by substitution of cheaper materials for some uses as prices of the original material rise. In summary, mineral products from extra-terrestrial sources will tend to increase the sustainability of human civilization, once steady state has been reached.

Jan 1, 2014

By M. Kalicinski, M. Lyssyy

"Access to information is a key component for making improvements to any process. This is particularly true for all aspects of the iron mining and steelmaking process. The ability to make rapid control decisions can significantly influence process outcomes, including ensuring product specification, mining quality, transportation limits, upgrade factors, waste bypass and direct shipping, among many others. While traditional laboratory methods provide feedback for such processes, having access to analysis results in real-time can lead to positive reactive and predictive control decisions to be made rapidly, leading to significant improvements throughout the process. Scantech has been designing, manufacturing and supplying technological products to the minerals industry since 2002 to enable the availability of such real-time information to a mine or plant, with the benefits being enjoyed by a wide range of operators. This paper provides a summary of the available technologies used in the iron ore and steel industries, as well as providing case studies of their use in African and Australian iron ore and European steel, as well as a description of the potential benefits of a range of analysis equipment.INTRODUCTION Access to information is critical for any process, and is a fundamental component for making process control decisions. In order to yield effective processing outcomes, it is important for that information to be readily available, preferably as quickly as possible, and to be as accurate as possible. While speed and accuracy are often traded off against each other, there are numerous technologies available in a processing environment that allow for both rapid flow of information and a high level of accuracy. The use of on-belt analysis equipment has a long trusted history of use in a number of mining and processing environments and industries, providing information such as elemental composition and grade of conveyed materials, moisture content, waste proportion and energy information. Australian company Scantech has been a provider of such equipment since 1981, and has become an industry leader in both the supply and development of on-belt analysers across a range of industries."

Jan 1, 2018

By D. Chakraborty, Neeraj Kumar

"The study provides the comparative analysis of the performance of water only cyclones and hydrocyclone for iron ore fines processing at Joda Iron ore processing plant, Tata Steel. Joda iron ore deposits have higher proportion of kaolinite in the finer fractions and are meant to be separated with cyclones. The iron processing flowsheet of Joda comprises of water only cyclone for beneficiation of iron ore fines. Water only cyclones are used for the beneficiation of fines in the iron ore processing industry and have a larger cone angle compared to that of conventional hydrocyclones to enhance the density effect in the separation. They are aimed to achieve better product quality of underflow however; the desired result could not be achieved at the Joda processing plant. The water only cyclones were operating at the corrected cut-size of about 60 micron with an imperfection of 0.40 and water split to underflow was approximately 10%. The overall Fe recovery from the water only cyclones were 60%. Since the quality of fines produced from the water only cyclone couldn’t be improved, an attempt was made to process the fraction in the conventional hydrocyclone to achieve the desired product quality. The trial results indicated better product quality with the Fe recovery of 72% at corrected cut-size of 70 microns and imperfection of around 0.29. In view of above results it was recommended to replace the water only cyclones with hydrocyclones to achieve higher product quality of about 60% Fe content.INTRODUCTION Water only cyclones were installed at wet plant, Joda to process the classifier fines where the cyclone underflow is considered as concentrate and overflow is discarded as slime. Because of the lower capacity of the cyclones 30% of the classifier overflow was bypassed directly to thickener. Apart from this the quality of fines produced from the water only cyclone couldn’t be improved further hence an attempt was made to process the fraction in the conventional hydrocyclone to achieve the desired product quality and quantity. Hydrocyclone was installed at Joda after replacing stub-cyclone and came into operation on 23rd Aug’ 2017.The process variables of water only cyclones and hydrocyclones are tabulated below:"

Jan 1, 2018

By Danilo Zim, Matheus Paschoalino, Denis Guimarães, Jasbir Gill

The shortage of water supply in some regions of the globe is particularly problematic and forces mining companies to adopt alternatives like pumping sea water from the ocean up to the mining sites. Although deaeration of sea water or the use of lined pipelines are known options to prevent corrosion during pumping, a recent development of a new corrosion inhibitor allowed the use of simple mild steel pipelines for this purpose. The objective of this study is to demonstrate the recent advances of this technology in protecting against not only general corrosion but localized corrosion, main cause of corrosion-related pipeline failures. Corrosion studies were carried out using electrochemical techniques, weight loss balance as well microscopy surface analysis in order to measure and therefore evaluate the treatment efficiency. The right dosage of corrosion inhibitors may vary depending on water composition and characteristics of each system. Differences were observed depending on the sea water source. Pretreatment of metallic surface impacts the observed corrosion rate which can be as low as 3.6 mpy. The absence of pitting or localized corrosion was achieved in aerated seawater.

Jan 1, 2014

By Ventsislav Stoilov, Angel Angelov, Ivan Korolev, Antti Remes, Todor Pukov, Stoyan Gaydardzhiev

"The process modeling and simulation studies aim for better process operation and favorable environmental impact. The objective of this work is to set up a simulation model of the Assarel copper flotation circuit for planning and optimization of the process with the aim of increased metal recovery. The model is parameterized based on laboratory flotation tests of ore samples from the Assarel mine together with mineralogical studies by X-ray diffraction (XRD) and Mineral Liberation Analysis (MLA). A combination of several techniques allows reliable identification of mineralogical composition of the selected samples. The changes in the proportion between sulfide minerals in various products along the circuit have been also documented. Further, this information is used in the simulation model and in data reconciliation procedures for establishing mass balance. The simulation accuracy is studied by comparing the simulations with the plant survey based mass balance. Constructed simulation model can be used to run alternative process scenarios. As an example, the flotation circuit performance with different reagent regimes is simulated based on data from batch flotation tests. Two reagents were considered for this purpose, dithiocarbamate-based one and xanthogen formate/mercaptan blend. It has been revealed that these reagents do not have the same influence on the selective flotation. The one improves flotation of gold and overall recovery but without notable selective action. In contrast, the other showed better selectivity towards copper, rejecting more gangue and lowering gold recovery. The model is also applicable for process optimization studies with different feed compositions, flowrates and circuit configurations. INTRODUCTION In the pursuit for elevated technological indicators, finding an optimal set of process parameters fully utilizing the potential of the equipment is a key factor to success. Over the past decades, there has been a substantial development in flotation circuit optimization through performance benchmarking using metallurgical modelling and steady-state computer simulation. Practical simulation engineering tools are based on experimental data obtained from laboratory tests and from plant surveys and operation data. With the help of flotation models, it is possible to study grade-recovery response with different feed compositions and throughputs, and with various cell-operating parameters, as well as to evaluate and design different flowsheet configurations. Outotec’s HSC Chemistry® software, which incorporates simulation and mass balancing modules alongside with several other tools, can assist with this optimization (Mattsson et al., 2015)."

Jan 1, 2018

By A. Lane

Africa is ripe with opportunity for the mining industry. The continent has large, and relatively unexplored mineral deposits, and recent high economic growth rates have meaningfully improved the political, economic, and infrastructural environments. However, these opportunities are accompanied by significant risks, including resource nationalism, uncertain regulation, corruption, and continuing political instability (up to and including war). Forward-looking companies actively manage these risks by creating a sense of shared purpose with the countries and communities that own the resources, using tools such as stakeholder analysis, local narratives, scenario planning, and constituency engagement. They also measure socio-economic impact to insure the creation and demonstration of shared value.

Sep 1, 2012

By Aidan Giblett, Karen McCaffery, Robert Dunne

"A worldwide decline in competency levels of practicing metallurgists over recent decades has become clearly evident and is a common topic of discussion among senior practitioners and professional associations. The associated impacts on the industry are material and include operational inefficiencies, missed optimisation opportunities and suboptimal new plant designs. There are many contributing factors to this condition. Decrease in competency is particularly evident both in regions where imbalance between supply and demand has led to a general reduction in experience levels for comparable roles over time and in emerging regions where a rapid rise in demand for practitioners has occurred in conjunction with rapid economic development and industrialization. The context, depth and breadth of education curricula and levels vary with location such that solutions to the technical competency dilemma may need to be developed specifically for each region with these influences in mind. Delivering, demonstrating and maintaining competencies are a critical requirement of undergraduate training and ongoing professional development. Other factors such as generational and cultural characteristics and expectations, political influences, role requirements and employment reward and recognition systems all play a critical role in determining if core competencies can be effectively developed, applied and subsequently maintained. This paper reviews factors impacting and some common approaches to competency development. The authors’ experiences in the management of professional development efforts within the global industry are reviewed and a blueprint proposed to address industry requirements in this area."

Jan 1, 2014

By V. Avdochin

The main reason of flotation process fluctuations is mixing ores of various properties from various sections of a deposit. Other, also important reasons are changes in parameters of facilities of technological cycle, as well as properties of reagents applied. According to estimates, instability and non-optimized parameters of flotation owe 3% to 6% of valuable component losses. Without ore averaging systems flotation process is characterized by considerable fluctuations of all input, output and intermediate parameters. Stab One more way is optimizing the process, providing for determination and maintaining optimal parameters of the process. In these conditions application of various mathematic models does not allow controlling the process by the way of action on input parameters of the process with further precise reaching required values of output parameters. More effective is to be application of flotation models for solution of questions of choosing and optimizing of automatic control systems. The work presented examples of application mathematic model of flotation process for estimation of effectiveness and choice of parameters of automatic control system that reduces considerably a stage of preliminary studies in elaboration, designing and modernizing automatic control systems.

Jan 1, 2014

By K. Sasaki, H. Miki, Y. Muta, T. Hirajima, G. P. W. Suyantara

"Selective flotation of chalcopyrite and molybdenite is continuing problem since its selectivity is not perfect and current NaHS process needs closed system flotation plant because of hydrogen sulfide emission on acidic condition. Some alternative additives investigated as chalcopyrite became hydrophilic and molybdenite kept hydrophobic. XPS analysis indicated chalcopyrite became hydrophilic since iron and copper sulphate, hydroxide was covered on the surface whereas molybdenite kept hydrophobic since only molybdenite can be seen. Flotation experiments of chalcopyrite and molybdenite mixture sample indicated excellent separation that 95% of molybdenite can be recovered as froth and 93% of chalcopyrite can be recovered as sink. Flotation experiments with real bulk flotation concentration indicated similar separation result compared with current NaHS additive system. Possible mechanisms and detailed phenomenon were investigated based on the surface analysis and thermodynamic calculation etc. this alternative additive is easy to handle compared with NaHS since it does not emit effluent gas and commercially preferable.INTRODUCTIONMany copper mine often associates molybdenite (MoS2) as trace mineral. It is important to separate molybdenite and copper mineral efficiently since molybdenite is valuable mineral and also contamination of molybdenite into copper concentrate decrease concentrate value. Conventional separation of copper sulfide and molybdenite has been achieved with sulfide bulk flotation followed by selective molybdenite flotation with NaHS addition since NaHS works as a depressant for copper sulfide (Bulatovic, 2010; Ansari and Pawlik, 2007b). However, this current process shows imperfect molybdenite recovery (Liu et al., 2012, Zanin et al., 2009) and depressant such as NaHS needs to be used under specific flotation plant since it might be environmental contaminant (Ansari and Pawlik, 2007a). there are still unknown on the effect of depressant NaHS, but one of the theory is NaHS reductant effect. It is worth to investigate the effect of other reductant as depressant on chalcopyrite. On this research, typical reductant, Na2SO3 are added to utilize for selective flotation of chalcopyrite and molybdenite."

Jan 1, 2018

By E. V. Manlapig, M. C. Harris

"The complexity of the flotation process has made the identification of an appropriate model structure, for use in the prediction of flotation circuit performance, far from obvious. Work performed under the auspices of the AMIRA P9 flotation program has indicated that the metallurgical performance achieved from a flotation cell arises from the interaction of two essentially independent property classes, namely the cell operating conditions and the properties of the cell feed stream. These observations have led to the development of a model structure that associates a constant set of flotation parameters to the streams of the circuit, which are transformed into a flotation response depending on the operating conditions within the flotation cell.A variety of alternative model structures exist within the literature which do not make this distinction between cell and stream flotation properties, and many of these models are in widespread use for flotation optimisation and design studies, both in industry and academia.In this paper, data collected from an industrial flotation circuit is used to derive the parameters associated with two different types of flotation models. Simulations performed using these models demonstrate the need to differentiate between cell and feed properties. A model that does not differentiate between these two properties fails to successfully predict the metallurgical performance of a flotation circuit after a disturbance."

Jan 1, 2003

By João Queiroz, Cristian Marquez-Sarmiento, Luiz Teixeira

The removal of various metals from process waters and effluents is usually done by precipitation of the corresponding hydroxide. Manganese however is one metal that does not respond efficiently to that approach. It may be seen in its eH X pH diagram that the way of oxidation to Mn IV rather than hydrolytic precipitation of the Mn II ion as its hydroxide, is the way to efficient precipitation of Mn in the pH range 6 to 10. We studied the use of oxidants O2; NaClO; H2O2; Caro´s Acid (H2SO5) and the combinations of O2 or H2O2 with Na2S2O5, and H2O2 with NaClO, for the oxidative precipitation of Mn from synthetic solutions starting with 10 mg/L Mn, at 25 oC. In adequate conditions, which include pH > 8, it is possible to reach final [Mn] less than 0.1 mg/L in 60 minutes of reaction time.

Jan 1, 2014