Jump to content


  • Content count

  • Joined

  • Last visited

Everything posted by zaqqaz22

  1. Thanks Chris for you input.. The article below defines the issues at play that I was querying and pretty much concurs with your input, and is based primarily on the difference in the definition of "Scientific" and "Industrial" measures of concentration. Although mainly dealing with solutions and air contaminants, there is also reference to metallurgical analysis. Taken from United States Naval Academy Website.. Link below http://www.usna.edu/ChemDept/_files/documents/manual/apdxN.pdf More "male bovine excrement" eric?? Take it up with the US Navy !!! Appendix N CONCENTRATION UNITS Chemists and engineers often encounter technical situations that require the description of the relative quantity of some substance in terms of its concentration in a solution or in air. For these purposes a variety of concentration units have been developed that can be used according to the needs and requirements of the job. Concentration units can be divided into two broad categories. There are those units that are used in research and scientific applications and those units that are used in industrial applications. These categories are not firm and fast, but they are useful in understanding when one unit is used in preference to another. Several common scientific and industrial units are listed below: SCIENTIFIC INDUSTRIAL molarity (M) mass percent (%) molality (m) parts per million (ppm) mole fraction (X) parts per billion (ppb) The primary difference between scientific and industrial units is that in scientific units the identities of the solvents and solutes are known and are usually pure substances; in industrial units, the solutes and solvents may be mixtures of materials whose composition is not well defined. The use of scientific units requires the calculation of a number of moles, therefore the molar mass must be defined. However, this requirement is not present with the industrial units. A. SCIENTIFIC UNITS 1. Molarity (M) Molarity is defined as: M = (mol solute)/(L solution) and is reported in units of mol/L or molar. Molar concentrations are the most common of the scientific concentration units because molar solutions are easy to prepare. In general, a molar solution is prepared by placing a known quantity of solute in a volumetric flask and adding solvent until the flask is filled to the calibration mark. Molar concentration is used in many common laboratory applications and is the concentration unit most frequently encountered in the general chemistry laboratory. One limitation in the use of molar concentrations is that the volume of the solution changes with temperature. This results in a change in the molar concentration. For work at constant temperature, however, this limitation does not exist. 2. Molality (m) Molality is defined as: m = (mol solute)/(kg solvent) and is reported in units of mol/1000 g, mol/kg, or molal. Molal concentration is less convenient to use than molarity because the mass of the solvent must be determined rather than its volume. In practice, generally only small quantities of these solutions are prepared and therefore this inconvenience is minor. Molal concentrations are used in experiments determining freezing point depressions, boiling point elevations, and in other cases where the temperature of the solution changes over the course of the experiment. Molal concentrations eliminate the problem of the dependence of volume on temperature seen with molar solutions because masses are not temperature dependent. 3. Mole Fraction (X) Mole fraction is defined as: X = (mol solute)/(mol solute + mol solvent) As with molality, preparing solutions using mole fraction units requires the weighing of solute and solvent so that the number of moles can be calculated. For many solutions, the quantity of solute is small compared to that of solvent, so the numerical values of mole fraction are frequently very small numbers. Because moles are the units of both numerator and denominator, mole fraction is a unit-less quantity. B. Industrial Units 1. Mass Percent (%) (or percent mass) Mass % is defined as: A similar relationship holds for volume percent (or percent by volume). % = (mass of solute) /(total mass of solution) x100 % = (volume of solute)/(total volume of solution) x 100 volume Mass percent is used to express the concentration of substances that are not pure, for example, the content of butterfat in milk. Butterfat is not a pure substance, but its mass percent in milk determines the legal difference between skim milk, whole milk, and table cream. Mass percent is also used in the metallurgical industry to describe the quantities of different components in alloys. Certain generic names such as "stainless steel" imply the presence of certain minimum levels of different components in the steel. In this case, the definitions are not legal ones, but are standard compositions accepted by industry. Examples are: COMMON NAME MASS-PERCENT ELEMENTAL COMPOSITION brass 67-90% Cu, 10-33% Zn dental amalgam 50% Hg, 35% Ag, 15% Sn 18-carat gold 75% Au, 10-20% Ag, 5-15% Cu stainless steel 73-79% Fe, 14-18% Cr, 7-9% Ni 2. Parts per Million Parts per million (ppm) is defined as: ppm = (mass of solute) / (total mass of solution) × 106 The unit “parts per million” is usually used for very dilute aqueous solutions. For very dilute aqueous solutions the density of the solution is assumed to be the same as the density of pure water (1.00 g/mL), so that one liter of solution has a mass of 1000 g and 1000 L of solution has a mass of 106 g. This information gives two additional definitions of parts per million. ppm = (g solute)/(1000 L solution) ppm = (mg solute)/(L solution) Parts per million is used to describe concentrations in solutions containing poorly defined or unidentified solutes or mixtures of solutes. Parts per million is also used to describe concentration levels to those who are unfamiliar with the concept of moles. Tap water contains a variety of dissolved impurities, mostly minerals. A simple way of describing the levels of these impurities, often called dissolved solids, is to measure out a sample, 10 mL for example, into a weighed aluminum cup and evaporate the water. The mass of the remaining solids is determined by difference. Dividing the mass in mg of remaining solids by 0.010 L gives the concentration of the dissolved solids in ppm. Notice that the identity of the solids is not specified, but a measure of their concentration is known. The Navy uses the level of chloride ions in boiler water as an early warning indicator for seawater leaks into condensers. The titration test that is used precipitates the chloride ions as a mercury compound. The chloride ions themselves are present in water along with many cations including sodium, potassium, magnesium, and calcium ions. Because it is not appropriate to talk about the amount of sodium chloride in the boiler water, the results from the mercury titration are used to determine the mass in mg of chloride ions in the sample and are in turn expressed as ppm of chloride. 3. Parts per Billion Parts per billions is defined as: ppb = (mass of solute)/(total mass of solution) × 109 For very dilute aqueous solutions the approximation is: ppb = (μg solute)/(L solution) Parts per billion is used for reporting trace contaminants of substances in water supplies and for substances present in extremely small quantities in other systems.
  2. Hello All. I am rather perplexed how the 1ppm = 1 gram per ton rule/assumption works.. Maybe someone out there who is an expert in the field of geochemistry/metallurgy might be able to help. I would have assumed that 1ppm literally meant 1 atomic or molecular PART per 1 million other atomic or molecular parts.. In consideration I would also have assumed the various atomic weights/masses of various elements would have a major impact on this assumption. Ie.. Given gold has a specific gravity of approx. 19.3.. and then if we can assume that the host material (silicates, carbonates, oxides etc) have an average combined SG of say 2.8. Then the sum I would have presumed would run like this; 1 ppm = 19.3 : 2.800,000 or 1.00 : 145,077 or 6.89 : 1,000,000 ie. 6.89 grams per ton.. when it comes to gold.. I got thinking about this when looking at assay result for scandium.. With an SG of 3.0 for Scandium, I find it hard to believe that 1 ppm scandium and 1 ppm gold would both equal 1 gram per ton of contained commodity.. It just does not ad up.. or am I missing something fundamental.. Or does PPM actually not mean PPM at all?? Any guidance or insights most appreciated !!! cheers Tony
  3. Nice one eric N. Your undoubtedly a real champion.. !!! Despite you opinion that Wikipedia is 100% drivel (as you would obviously know), it is stated in the Wiki article even the "Real Authorities" at the BIPM have major issues with the PPM notation for the exact same reasons I have.. Feel free to write them an email and tell them how stupid and overly academic they are being too, in-between mining your next million ounces that is, you rocket scientist you!! Anyways. I did finally get in touch with a "real" practicing industrial chemist, who was kind enough to Politely inform me that indeed, in the modern world when doing "metallurgical style" chemical analysis the results are first analysed as mg/kg (just like in the good old days).. but now days these are transposed into PPM, something that he even admitted was not ideal and can cause confusion between the various fields of science.. Hope I am not "overthinking" and getting too academic for you again eric?? BTW, gold in ore deposits is does not have an SG of 19.3??? for a self proclaimed genius you a right off track there, or should I have used 19.32 at 20 degrees Celsius maybe?? .. Before you get your knickers in a twist again, my analysis is for gold, not native alloys, fineness does not come into it.. Since you are such a genius eric, you really need get on Wiki and rewrite everything there is to know about gold, assaying, chemistry.. etc etc. us poor regular folk are obviously being intentionally deceived and misinformed by those evil pimply faced basement trolls.. You obvious have some degree of knowledge. shame you have no manners, no humility and no tact whatsoever.. In fact you seem to be propagating the exact same "troll like" online persona as those pimply faced social misfits lurking in their mothers basement, that you infer are polluting Wikipedia with all that so called irrelevant mindless garbage.. Just to rub it in, I will say it again "PPM notation needs to scrapped." . it is a unit-less ratio and can been misinterpreted. there, boohoo over that..!! As far as gold/ commodity analysis goes mg/kg or g/t is much more pertinent. !! Now finally, just to let you know I might be a bit rusty having not worked in the Mining Industry for 20 odd years, but I am actually a Geologist by University education. (Major Geology, Sub Major Physics..)... And yes, during my time working both in mines in Australia and on numerous exploration projects world-wide, I oversaw literally thousands and thousands of samples and assays, primarily for gold.. ALL done in grams per ton... NOT PPM. !!!! I might indeed have been over-thinking on this subject.. Guilty as charged.. But you?? brusque ?? quite a word, but it does not really do you justice eric, regardless, thanks for the education... Troll 101.. Since you are such a genius btw eric, here's another one for you, when I am getting analysis back from a Niton gun (XRF), for % of Scandium but intend on extracting the metal as an oxide, then what conversion should I make to compensate for this?? do tell.. Seems I can throw away all my chemistry books and banish Wikipedia, I have eric the oracle.. Now you can get back on your soap box and pontificate some more eric !!! King Kong and his Keyboard.. All yours buddy..
  4. I think the general concept I am using is correct.. 1 ppm is indeed a small amount no doubt, this is beyond question, but if we assume an assay of 1 ppm or 2 ppm equates to 1 g/t or 2 g/t then all of a sudden a 1 ppm variance can mean the difference between an economically viable gold deposit a uneconomic gold deposit.. So in large scale mining these very small numbers can have huge consequences.. Though this is not really my point.. My point is; if assays and chemical analysis are done as molecular analysis. (i.e. mole's), which I assume they are?.. Then the results are a ratio of atoms/molecules etc.. Considering these atoms/molecules have varying masses/densities, then correlating the results straight from Mole : Mole ratios to Mass: Mass ratios (i.e. grams per ton) will require a conversion factor based on the different densities of the particular substances involved.. This is given as an example in the Wiki article with gasses, in this case CFC-11, in which case to convert mole fractions to mass fractions the conversion factor is 4.7.. So to get back to my initial calculations, which seems to have confused everyone.. let me try re-represent them; ie for gold - SG - 19.3 g/cc - Gangue rock (mix, silcates, sulphides, carbonates) - SG 2.8 g/cc (approximation, for example..) 1 ppm gold molecular analysis (i.e. mole) 1: 1,000,000 So for mass we would then need to apply the SG's for gold and host rock (Gangue).. (1 x 19.3g/cc) : (1,000,000 x 2.8g/cc) 19.3 : 2,800,000 Ok so now to get it back to 1,000,000 or 1 ton if applying to grade. we need to dived both sides by 2.8. 19.3/2.8 : 2,800,000 /2.8 6.89 : 1,000,000 or 6.89 g/t.. Anyways, this is all rather academic.. And I suppose the ultimate question is to a practicing industrial chemist or a metallurgist.. When assaying/analysing for economic elements / minerals, is the analysis done as a molecular (mole:mole) analysis? - in which case to convert to g/g would need a conversion factor for mass.. And in which case there is no way 1ppm gold and 1 ppm scandium can both work out at 1 gram per ton.. (my original Q !!).. Or is the analysis done stickily by mass:mass .. in which case the answer is simple and 1ppm of anything analysed would equal 1g/t It is well worth reading the wiki article on this.. seems the PPM notation causes confusion all over, especially between differing fields of science.. So i'm not the only one !!.. Seems PPM notation needs to be scrapped !!!
  5. Jeepers!!!! wish I was digging 10,000 ppm gold dirt?? that would be over 320 oz per ton.. !!! Ok, so I think you have nailed it with your last line.. "PARTS" in PPM must not literally mean "PARTS" on a molecular or atomic level.. otherwise the Atomic mass of the elements would have a large impact on the conversion to grams per ton.. This is what I was initially trying to fathom.. But I think you are right, PPM represents a weight to weight ratio... The boffins need to change the nomenclature, the term is misleading. funny just found this on Wiki.. this is the exact problem... the diff between a Mass Fraction and a mole fraction.. Seems even the ruling international body of weights and measures has issues with PPM as well “a continued source of annoyance to unit purists has been the continued use of percent, ppm, ppb, and ppt.” Mass fraction vs. mole fraction vs. volume fraction[edit]Another problem of the parts-per notation is that it may refer to mass fraction, mole fraction or volume fraction. Since it is usually not stated which quantity is used, it is better to write the unit as kg/kg, mol/mol or m3/m3 (even though they are all dimensionless).[8] The difference is quite significant when dealing with gases and it is very important to specify which quantity is being used. For example, the conversion factor between a mass fraction of 1 ppb and a mole fraction of 1 ppb is about 4.7 for the greenhouse gas CFC-11 in air. For volume fraction, the suffix "V" or "v" is sometimes appended to the parts-per notation (e.g., ppmV, ppbv, pptv).[9][10] Unfortunately, ppbv and pptv are also often used for mole fractions (which is identical to volume fraction only for ideal gases). The usage is generally quite fixed inside most specific branches of science, leading some researchers to draw the conclusion that their own usage (mass/mass, mol/mol, volume/volume, or others) is the only correct one. This, in turn, leads them to not specify their usage in their publications, and others may therefore misinterpret their results. For example, electrochemists often use volume/volume, while chemical engineers may use mass/mass as well as volume/volume. Many academic papers of otherwise excellent level fail to specify their usage of the parts-per notation. here in link.. https://en.wikipedia.org/wiki/Parts-per_notation