# A Glossary of Common Terms



## FrugalRefiner (Sep 23, 2014)

*A Glossary of Common Terms*

The purpose of this glossary is to provide simple definitions of terms. It is not intended to be a comprehensive discussion of any term or description of any process. In fact, entire books have been written about some of these terms. With the information provided below, the reader should be able to conduct further research on any subject that interests them.

*AC* - An acronym for Acid Clorox, a combination of hydrochloric acid (HCl) and Clorox bleach. Clorox is a brand name for household laundry bleach which is a 3 to 8 percent solution of sodium hypochlorite (NaClO). This combination can dissolve gold, platinum, and other metals. (aka A/C)

*activity series* - A list of ions and/or metals ranked in order of their relative reduction potentials. The more highly reactive materials lose electrons more easily to form positive ions. See also reactivity series, electromotive series.

*agglomerate* - To collect or gather together into a mass. When a metal in solution is precipitated, microscopic particles _agglomerate_ into visible particles through grain ripening. Stirring and/or heating can help the particles _agglomerate_ into larger lumps.

*aliquot* - A sample of a solution used for analysis of the solution.

*anion* - A negatively charged ion, e.g., Cl- or NO3. See also ion, cation.

*AP* - An acronym for Acid Peroxide, a combination of hydrochloric acid (HCl) and hydrogen peroxide (H2O2). It is a leaching solution that can be used to dissolve many metals. Although the starting chemicals are hydrochloric acid and peroxide, these solutions react with copper to create copper(II) chloride (CuCl2) etchant, which then dissolves more metals. (aka A/P) Acid Peroxide Process Information Thread Q & A's

*AR* - An acronym for Aqua Regia, a combination of hydrochloric acid (HCl) and nitric acid (HNO3) that can dissolve gold, platinum, and many other metals. Aqua regia is typically a mix of approximately 3.5 parts of HCl to 1 part HNO3, with the nitric being added in increments to avoid using too much.

*azeotrope* - An azeotrope is a combination of two or more liquids and/or gases in which the relative concentration of the components cannot be changed by simple distillation.

*BDG* - An acronym for Butyl Diglyme, a solvent which can be used to selectively separate gold that is in solution from other metals in the same solution.

*BFRC* or *BRFC* - An acronym for Big Freaking Red Cloud, or Big Red Freaking Cloud, a slang term for the brownish red gas given off by nitric acid when it reacts with other substances. See also NOX.

*BGA* - An acronym for Ball Grid Array, a type of integrated circuit package that uses small balls of solder on the bottom of the package to connect to the circuit board instead of pins or legs.

*butyl diglyme* - An ethereal solvent which can be used to selectively separate gold that is in solution from other metals in the same solution. (aka dibutyl carbitol, BDG)

*calcine* - Heating a chemical compound to cause it to beak down into it's components, usually with part of the compound being driven off as gas leaving the other part behind, e.g., _calcining_ ammonium hexachloroplatinate to pure platinum sponge.

*carrier* - A metal that, because of its affinity for certain other metals, can cause them to follow the carrier through a refining process. Examples include silver for PGMs, lead for PMs in assaying or smelting, zinc for PMs in molten lead (see Parkes Process). See also collector.

*cation* - A positively charged ion, e.g., Au3+ or Ag+. See also ion, anion.

*cementation* - A type of reduction precipitation in which a more reactive, solid metal replaces a less reactive (more noble) metal that is already in solution. The less reactive metal comes out of solution as fine solid particles, which, after they settle, look somewhat like wet cement. See also reduce, replacement reaction.

*charge* - A quantity of material placed in a crucible or melting dish for the purpose of melting it. See also heat.

*collector* - A substance used to gather metals which are in small quantity to aid in separating them from the gangue and/or flux. Lead is commonly used as a collector in assaying and smelting. See also carrier.

*colloid* - A combination of materials in which one exists in very small, insoluble particles which do not settle out of another while it is in a liquid phase. They are suspended by Brownian motion. Colloids can be broken by heating to cause the particles to agglomerate, or by manipulation of the solution's concentration.

*copperas* - An old name for ferrous sulfate (FeSO4), a selective precipitant for gold. The name comes from the green color of the solution which appeared to be "coppery water". (aka iron(II) sulfate, green vitriol)

*cornflake* - A term for metal which has been melted, then poured into cold water to form small, somewhat flattened pieces of metal which resemble corn flakes. This form maximizes the surface area of the material, which facilitates leaching or dissolution. Also used to describe the process of creating the cornflakes. See also granulate.

*CPU* - An acronym for Central Processing Unit, usually the main integrated circuit in a personal computer or other electronic devices.

*crucible* - A container that can withstand the heat of a furnace and holds a molten charge of metal and/or fluxes.

*CuCl**2* - The active component in the process commonly referred to as Acid Peroxide, or AP, or copper(II) chloride. In solution, it is used as a leach to dissolve copper and other base metals prior to dissolving precious metals.

*cyanide* - A chemical compound that can be used to put some precious metals into solution. It is extremely toxic and highly regulated in most locations.

*decant* - To pour or draw off a solution from one container to another, used to separate a solution from a precipitate.

*deNO**X* - To remove excess nitric acid from an aqua regia solution prior to precipitating the values.

*dibutyl carbitol* - A solvent which can be used to separate gold that is in solution from other metals in the same solution. (aka butyl diglyme)

*digest* - To dissolve a substance into a solution.

*dimethylglyoxime* - A chemical used in testing for the presence of palladium or nickel in a solution, or selectively precipitating palladium.

*DMG* - An acronym for dimethylglyoxime, a chemical used in testing for the presence of palladium or nickel in a solution, or selectively precipitating palladium.

*doré bar* - An impure bar of metals that results from recovery processes which is ready for refining procedures.

*drop* - A jargon term for precipitation. It is used as a verb, e.g., I'm going to _drop_ my gold, as well as a noun, e.g., The _drop_ went well.

*electrolyte* - A solution that conducts some electric current, used in electrolytic cells.

*electrolytic refining* - A process that uses electric current and an appropriate electrolyte to dissolve a metal from an impure anode and deposit it as a pure metal at the cathode.

*electromotive series* - A list of substances, similar to the activity series, ranked in order of their relative tendency to gain or lose electrons. See also activity series, reactivity series.

*electrowinning* - A process that uses electric current to cause a substance that is dissolved in a solution to be deposited as a solid metal at a cathode.

*eutectic* - A mixture of metals that melts as a whole at the same temperature. The eutectic temperature of such a mixture has the lowest possible melting point of any percentage mix of the components.

*evaporate* - To heat a solution to a temperature below its boiling point for the purpose of reducing the volume of the solution or reducing or eliminating a more volatile component of the solution.

*exothermic* - A process or reaction that releases energy, usually in the form of heat. The opposite of endothermic.

*filtrate* - The liquid that passes through a filter.

*fingers* - Card edge connectors from printed circuit boards that are designed to be plugged into compatible sockets. They are commonly found on personal computer add-in boards, RAM, some processors, etc.

*fizzer cell* - An electrolytic cell, that produces gas as a by-product, used to dissolve gold and keep it in solution. It uses a porous cup or membrane to separate the anode from the cathode, which prevents the gold from plating out on the cathode.

*flocculation* - A process, requiring a flocculating agent, where solid, suspended particles are separated from a liquid and settle as a loose precipitate. See also agglomeration.

*fusion* - The process of melting one or more substances or dissolving a solid substance in a molten substance, or the result of that process.

*gangue* - The bulk, insoluble material from which precious metals are recovered, e.g., the rock from a precious metal bearing ore.

*gold parting cell* - An electrolytic refining cell used to separate gold from other metals. See also Wohlwill cell.

*gold stripping cell* - An electrolytic recovery cell which uses electric current and concentrated sulfuric acid to remove the gold from gold plated material.

*granulate* - A process of melting a metal, then pouring it into cold water for the purpose of creating small pieces with a large amount of surface area, for the purpose of dissolving it (or some part of it) into solution. See also cornflake.

*HCl* - The chemical formula for hydrogen chloride, a gas, which is dissolved in water to create hydrochloric acid. (aka muriatic acid)

*heat* - The material placed in a crucible or melting dish that is to be melted. See also charge.

*HNO**3* - The chemical formula for nitric acid.

*H**2**O2* - The chemical formula for hydrogen peroxide, a strong oxidizer.

*H**2**SO4* - The chemical formula for sulfuric acid.

*IC* - An acronym for Integrated Circuit. Many integrated circuit packages contain precious metals.

*in situ* - To generate a substance or a reaction "on place", or "in position", or in the midst of. Adding Clorox bleach to hydrochloric acid releases chlorine _in situ_.

*incinerate* - To heat material to a dull red heat in the presence of oxygen. The process is used to eliminate organic materials, to convert certain elements and/or compounds to oxides, and to eliminate chlorides or nitrates when switching acids.

*inquart* - The process of adding base metal to a gold alloy to bring it to a level of twenty-five percent (one quarter) gold and seventy-five percent base metal to facilitate leaching of the base metals from the alloy.

*ion* - An atom or group of atoms in which the total number of electrons is not equal to the total number of protons, giving the atom a net positive or negative electrical charge.

*leach* - A solution used to selectively dissolve certain elements or compounds from an insoluble matrix, or the process of using such a solution.

*liquor* - A liquid which contains metals in solution.

*litharge* - A name for lead(II) oxide (PbO), a compound commonly used in assaying and smelting.

*lixiviant* - A name for a leaching solution. See also leach.

*melting* - The process of using heat alone to convert a solid material to a liquid phase, not to be confused with smelting. See also smelting.

*melting dish* - A wide, shallow dish usually made of fused silica and clay, it is the preferred container for melting small quantities of precious metals with a torch.

*Miller Process* - A refining process in which chlorine gas is passed through a clay tube into impure, molten gold, which causes most metal impurities to form volatile or stable chlorides which are then removed from the gold as fume or slag.

*MLCC* - An acronym for Multi-Layer Ceramic Capacitor, an electronic component that may contain precious metals such as palladium and/or silver.

*mother liquor* - The bulk of the liquid from which a precipitate has been removed.

*MSDS* - An acronym for Material Safety Data Sheet. An MSDS exists for virtually every chemical that lists the hazards, first aid measures, fire fighting information, storage and handling guidelines, etc. for the chemical. The forum has an area where you can find relevant sheets here: MSDS Sheets on Chemicals

*muriatic acid* - Another name for hydrochloric acid.

*NOX* - Any of several corrosive, irritating oxides composed of nitrogen and oxygen that are the decomposition and/or by-products of using nitric acid.

*oxidize* - As used in refining, to remove one or more electrons from a substance, resulting in an increase in the material's oxidation state. When a solid metal is dissolved in acid, it is oxidized. See also reduce

*Parkes Process* - A recovery process used to recover precious metals from molten lead. In the process, zinc metal is mixed into molten lead which contains precious metals. The zinc combines with the precious metals, then rises to the top of the liquid lead where it can be removed for further refining.

*parting* - The process of separating two or more metals from each other.

*PCB* - An acronym for Printed Circuit Board.

*PGMs* - An acronym for Platinum Group Metals. They are platinum, palladium, rhodium, iridium, osmium, and ruthenium, sometimes also referred to as the platinum sisters.

*pins* - Connectors used in many electronic components. These pins are often plated with precious metals.

*PMs* - An acronym for Precious Metals.

*poor man's aqua regia* - A combination of hydrochloric acid and either sodium nitrate or potassium nitrate to create a form of aqua regia. The sodium nitrate or potassium nitrate replaces the nitric acid, which for many, is expensive and difficult to obtain.

*poor man's nitric acid* - A process using sulfuric acid and sodium nitrate or potassium nitrate to make an impure form of nitric acid. The sodium nitrate or potassium nitrate and the sulfuric acid are less expensive and easier to obtain for many. Alternate Nitric Recipie - All Rights Reserved

*PPE* - An acronym for Personal Protective Equipment, which includes items such as gloves, aprons, face shields or safety glasses, respirators, etc. PPE should be used as a last layer of protection in case other measures are not sufficient.

*precipitate* - To cause a substance which is dissolved in solution to be converted to a solid. Also, the substance that becomes a solid.

*precipitant* - A substance that will cause precipitation of a substance that is in solution. A selective precipitant will cause only one or only a few substances to precipitate when many are in solution. A non-selective precipitant will cause most or all substances to precipitate.

*pregnant solution* - A solution in which precious metals are dissolved.

*prill* - A small, usually rounded, particle or glob of an element or compound.

*prill hold up* - A description of potential loss when micro BBs or fines refuse to agglomerate in the molten slag or flux.

*pyrolysis* - Heating of an organic substance in the absence of oxygen causing it to partially decompose.

*qualitative* - Describing something in terms of it's quality instead of its quantity, e.g., If a drop of HCl creates a white, cottage cheese-like precipitate, you probably have silver in solution. See also quantitative.

*quantitative* - Describing something in terms of the measurable properties, like weight, volume, size, etc., e.g., 1 liter of 1 molar HCl can precipitate 143.318 grams of silver chloride (AgCl). A reaction that goes to completion. See also qualitative.

*reactivity series* - A list of substances ranked in order of their relative reactivity. The more highly reactive materials lose electrons more easily to form positive ions. See also activity series, electromotive series.

*recovery* - Recovery processes separate value bearing materials from the majority of the waste material/gangue. The concentrated material may still contain a significant amount of impurities, but it is concentrated enough to move to refining processes.

*redox* - A combination of the words reduction and oxidation which describes chemical reactions in which substances have their oxidation states changed by losing or gaining electrons.

*reduce* - A gain of one or more electrons by a substance, resulting in a decrease in its oxidation state. When a metallic powder is precipitated from solution, it is reduced. See also oxidize.

*refining* - To make a metal fine. Refining processes convert high quality waste and concentrates to purified metals.

*reflux condenser* - An apparatus placed above a reaction vessel that causes some part of a volatilized substance to condense and drip back down into the vessel.

*replacement reaction* - A reaction that occurs when a more reactive, solid metal reduces a less reactive metal that is already in solution to a solid. See also cementation.

*report* - To end up in, or appear in, e.g., a contaminant that will _report_ in the final refined material.

*shot* - Small rounded beads of metal. Also, the process of creating the beads, e.g., _shotting_ the melted gold.

*silver chloride* - Silver chloride (AgCl) is an insoluble salt of silver. It is typically formed when adding a chloride compound, e.g., sodium chloride (NaCl), potassium chloride (KCl), hydrochloric acid (HCl), etc. to a solution containing dissolved silver (Ag+).

*silver nitrate* - Silver nitrate is a soluble salt of silver. When silver (Ag) is dissolved in nitric acid (HNO3) the result is silver nitrate (AgNO3) in solution.

*silver parting cell* - An electrolytic refining cell used to refine silver to a high degree of purity, in either a horizontal (Thum or Balbach-Thum) or vertical (Moebius) configuration.

*SMB* - An acronym for Sodium Metabisulfite, a selective precipitant for gold. (aka sodium pyrosulfite,

*smelting* - A thermochemical reaction that uses both heat and chemical reaction(s) to recover metals from other materials, not to be confused with melting. See also melting.

*solder mask* - A paint like substance applied to printed circuit boards that prevents solder from sticking to portions of the circuit where it is not desired.

*soxhlet extraction* - A process used to separate substances when the target material has limited solubility in the solvent being used and the impurities are insoluble. The soxhlet apparatus causes the solvent to be recirculated repeatedly through the sample, dissolving a little more of the target material with each cycle, which reduces the amount of solvent required. (aka continuous extraction)

*sponge* - The fine metal powder remaining as the result of calcining certain precious metal salts.

*SSN* - An acronym for Saturated Salt and Nitric acid, a combination of water that has been saturated with salt, and dilute nitric acid used as a leach.

*stoichiometry* - The calculation and balancing of the relative quantities of reactants in a chemical reaction such that all reactants are consumed in creating the product(s) of the reaction.

*take up the solution with...* - To add a liquid to a concentrated solution to create a more dilute solution.

*turbidity* - Cloudiness resulting from solids suspended in a solution.

*values* - The precious metal being recovered and/or refined.

*volatilize* - To cause a substance to pass off as vapor.

*watch glass* - A dish shaped piece of glass that is placed over a beaker or similar reaction vessel with the concave curve up, causing steam, mist, or droplets from the solution to condense on its lower surface, which then runs down to the lowest point in the center and drops back into the vessel.

*Wohlwill Cell* - An electrolytic refining cell, using gold chloride solution as the electrolyte, that can refine gold to a high degree of purity.

*XRF* - An acronym for X-Ray Fluorescence, a technique used to measure the components of a solid substance, like a bar of metal.

*yield* - The amount of precious metals obtained from the recovery and refining processes. Yields can differ between persons and processes, and even among similar material depending on when and where it was manufactured.


I'm sure my list is not complete. I welcome all feedback and suggestions. I do want to keep this list manageable, so please keep suggestions for new terms to those that might be confusing to new members, not simple terms they can look up on Google.

I would also like to add links so that readers can find additional information on subjects that interest them. I added the first ones to MSDS and poor man's nitric acid. If you know of a thread that you feel would be a good link for further information, please let me know.

I want to thank 4metals, butcher, Göran (g_axelsson), Harold and especially Lou for their help on this project.

Dave


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## Geo (Sep 23, 2014)

Thank you Dave. Very well done.


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## butcher (Sep 23, 2014)

Dave 
Your hard work, and thoughtfulness, to help others is appreciated, thanks for making this forum a great place to learn from.


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## Silver Sliver (Sep 24, 2014)

Thank you for this Dave.


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## philddreamer (Sep 24, 2014)

Thank you, Dave! 8) 

Phil


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## Claudie (Sep 24, 2014)

A very informative list, well done. 
Maybe add "Mixture" & "Solution" so people will learn the difference and use the terms correctly.


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## lazersteve (Sep 26, 2014)

Great list. I'll add a link to it in the Guided Tour.

Steve


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## pattt (Sep 26, 2014)

Hey Dave, 

I just wanted to say thank you for this list and your contributions to the forum.
I am still reading nearly all the new posts everyday but the work just doesn't leave me much time
to post myself, in the next few weeks i'll know if I can stay at the job or not, I'll let you know when I know 8)

Pattt


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## FrugalRefiner (Sep 26, 2014)

Thank you for the comments everyone!

Steve, thank you for adding it to the Guided Tour. I'm honored.

Dave


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## Phoenix76 (Jul 10, 2015)

Dave, I know you first posted this way back in September last year, but I've just found it. Perhaps we're a bit slow down hear on Australia, but it just shows what can be found on the forum if you go looking. I was just filling in time poking around the forum.

Mate, that's a great job you've done. I know a lot of the abbreviations but obviously not all of them. This will make a great reference piece for my ever growing refining library. Any newcomer to the forum and particularly refining, really should investigate what is on the forum; and of course they should read Hoke.

Down here we don't have much in the way of PM forums or even normal scrap forums, and the ones we do have are quite short on knowledgeable input. I think most of the PM scrappers here are very unsure of the processes so they don't offer much information. Guess that's good actually, because at least they aren't giving people bull**** about dangerous refining processes they know nothing about.

Know I don't post much on the forum, but I certainly read a lot of the posts and learn from them.

Anyway Dave, keep up the good work.


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## FrugalRefiner (Jul 10, 2015)

Thank you for the kind words. I'm honored that you made your first post here after being a member for over three and a half years. Comments like yours give me inspiration to continue working on projects like this.

Dave


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## scrapparts (Oct 14, 2017)

Add these to the glossary

chloride
oxygen sparging
nitrate


scrapparts


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## JoeyJoystick (Jul 17, 2019)

Hi Dave, 

Great list but haven't you forgotten the most important one? GRF = Gold Refining Forum. I have always struggled with abbreviations. I can imagine that newbees, like myself, that have similar lacks in language skills may struggle with this as well..  

Joey


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## FrugalRefiner (Jul 17, 2019)

Always good to see this thread get bumped!  

I suppose there are a few terms I should add. 8) 

Dave


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## Q-Ball (Jun 18, 2020)

This glossary alone was worth signing up. Love it.


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## Saddiq NG (Jul 5, 2022)

FrugalRefiner said:


> *A Glossary of Common Terms*
> 
> The purpose of this glossary is to provide simple definitions of terms. It is not intended to be a comprehensive discussion of any term or description of any process. In fact, entire books have been written about some of these terms. With the information provided below, the reader should be able to conduct further research on any subject that interests them.
> 
> ...


Thanks Dave. There was a term a yggdrasil used while he was advising me it is called
Sacrificial metals: he was referring to metals used to cement PGM metals since they may likely end up in the waste container.


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