Acids and Bases

Acids and Bases
Introduction : 

Everyone United Nations agency has worked with and/or prospected for gold has on a minimum of many occasions been forced to use acids or bases in one type or another. These chemicals will be indispensable for cleansing concentrates, cleansing mercury, recovering mercury, gold, silver from solutions of the salts and many different applications, several of that most people don't seem to be even aware. i'm reaching to try to justify some of the characteristics, uses and precautions that everyone ought to be aware of once exploitation these chemicals.

What they're
First the acids. what is Associate in Nursing acid? As we have expressed in different pages on this website, Associate in Nursing acid may be a chemical that once diluted with slightly water offers a pH scale of less than 7. Acids square measure classified into 2 major teams. robust acids and weak acids. robust acids square measure typically acids like sulphuric, hydrochloric, nitric, and phosphoric. examples of weak acids square measure carboxylic acid, carbonic, acid and ascorbic.

Furthermore, acids square measure classified as to their composition. There square measure inorganic acids and there square measure organic acids. Basically, the word "organic" means, "containing carbon". So, of the above mentioned acids the robust acids square measure all "inorganic" and therefore the weak acids square measure all "organic acids. O.K., someone goes to leap right down my throat due to the actual fact that carbonic acid will contain carbon. However, it is typically thought-about the exception to the rule. The rule is that most inorganic acids square measure robust and most organic acids square measure weak.

Bases square measure simply the opposite of acids. they offer a pH scale of more than 7 in water answer. As above there square measure robust bases, weak bases, inorganic bases and organic bases. some of the additional useful bases square measure sodium hydroxide (caustic soda), hydrated oxide (lye), ammonium hydroxide (ammonia) and hydrated lime (slaked lime). These square measure all robust bases. The weak bases have very little sensible use in mining therefore we are going to simply ignore them. only one example of a weak base, sodium hydrogen carbonate (baking soda).


Some Characteristics of Acids and Bases
At this time we have a tendency to square measure only reaching to mention the robust acids and bases that square measure useful in the prospecting/mining business. Acids and bases are available totally different strengths. Some acids square measure "stronger" than others. This "strength" is expressed as "normality". Hooray!! we have a tendency to don't seem to be going into that except as a reference as to relative strengths of acids/bases. this can offer you a concept of these relative strengths. the higher the normality, the "stronger" the acid.


 sulfuric acid H2SO4 - 36N
 acid HCl - 12N
 nitric acid HNO3 - 16N
 ammonium hydroxide - 15N
   
As you'll be able to see from these numbers focused sulfuric acid is thrice as robust as acid. it might take thrice as much} hydrochloric to neutralize X amount of base as it would sulfuric acid.

Precautions and handling
It is not continually the strength of the acid or base that determines however it is reaching to have an effect on you if you get some on you. for instance, nitric acid can burn you. it will produce a brown, discolored patch on your skin. this can be superficial (surface) only unless it stayed on you too long. On the other hand, sulphuric can almost instantly cause deep burns that don't seem to be superficial. this can be as a result of sulfuric acid includes a nice affinity for water. it will literally attack water where it finds it and produces scores of heat. this can be what causes the burns. Another characteristic of sulfuric acid is that it destroys cotton article of clothing. Same reaction like water. you probably will not notice your Blue Jeans till you wash them then you discover that they're currently only concerning one area unit of holes. This affinity of sulfuric acid for water is why you never pour water into focused sulfuric acid. The reaction and liberation of heat will be, and usually is, violent. It will be explosive and ruin your whole week by souse you in hot focused sulfuric acid. listen to Pine Tree State, DON’T do that. there's Associate in Nursing previous crutch to assist you bear in mind how to combine any robust acid with water. "Do such as you outta, put the acid in the water". NOT the other way around. this can be an honest rule to follow once diluting any robust acid however particularly sulphuric.

Now, slightly concerning robust bases, hydroxide, lye and ammonium hydroxide. Do any of you recognize of something that may burn you additional seriously than sulphuric acid? No? Well let Pine Tree State tell you what it is. robust solutions of robust bases. robust solutions of hydroxide or lye square measure terribly deceptive. They don’t sting or burn or hurt now. they merely feel "slick", such as you had oil on your hands. have you ever got whitener on your hands and they feel "slick" and you can’t wash it off? the explanation you can’t wash it off is that bases penetrate skin now. currently whitener isn't a true robust answer, only 5%. It ain’t NOTHING compared to an honest robust answer of lye. Have any of you guys ever created home-brewed soap? you're taking fat and treat it with lye. that is exactly what happens once you compass on you. It converts all the oils and fats in your skin, that partly protected you from the acids, into soap and alcohol. The slick feel. With no protection lye or caustic can penetrate your skin in seconds. And, it kills everything as it goes. No pain, no burns, however in a few hours your skin can simply slide off onto the ground going raw, exposed, muscle tissue. it is painful and extremely slow healing. One different point; bear in mind, chemicals react dependent on temperature. If you raise the temperature ten C the speed at that a chemical reacts or burns you doubles. Hot caustic is something you do NOT wish on you.

The moral to this story is, use sense, use plastic gloves and if applicable, face protection. DON’T GET HURT!!

Salts
Salts? however did we have a tendency to get to that? Thought this page was concerning acids and bases. Well, you just can’t mention acids and bases without discussing salts. Salt! That’s what we have a tendency to placed on tater etc. Yeah, that’s one salt, sodium chloride. There square measure thousands of others that you just undoubtedly wouldn't wish to put on the fries. So, what the ----- may be a salt? Glad you asked! A salt is the chemical that is formed once Associate in Nursing acid reacts with chemicals with a base. And, some of them react violently therefore you should know slightly concerning them. I ain’t gonna allow you to get hurt if you will simply droop with Pine Tree State. if truth be told the full point of this site is to allow you to use chemicals to get your job relinquished getting into hassle. currently we know what a salt is, additional or less. Example; if you're taking some acid (you really wouldn’t wish to drink it) and a robust answer of hydroxide (you damn well better NOT drink it) and you begin mixing the two you will notice that the solution starts to get hot. It’s reacting. If you're taking some "pH paper" and add one to the other till the pH scale is 7or neutral you have created a salt. you're a chemist as a result of you have simply reacted Associate in Nursing acid with a base to make a salt with the liberation of energy as heat. Now, don’t you are feeling great! you did it, you created a salt. however do you know you did? It still simply appears like water with some acid and base in it. The pH scale is 7, neutral, neither acid nor basic. Why can’t I see a change? as a result of the salt you created has no color. however am i able to see what I made? simple, evaporate the water and you will currently find a white crystalline substance left behind. this can be your salt made from poisonous hydroxide and poisonous acid. NOW, you'll be able to take these items and put IT ON YOUR FRENCH FRIES! you have succeeded in making sodium chloride, common table salt!! How’s that for a exercise of basement chemistry. I’m positive some of you will feel that you just have been "took". All that simply to find out how to create table salt? Why waste the time? If you understood it then it WASN’T a waste. you'll be able to currently apply constant reasoning to make any salt you would like. If you had used lye rather than caustic you would have made potassium chloride (salt substitute). The reaction we have a tendency to simply created is depicted as:

HCL + NaOH ------à NaCl + HOH (H2O).


Hydrochloric acid plus sodium hydroxide yields sodium chloride and Water. This same reasoning can apply to any acid/base reaction. But, the important question is why would i would like to make a salt anyway? I’m gonna get to that in my very own bungling, basement way. may even create it the foremost important factor in your prospecting career. If you're still with Pine Tree State and perceive the above, CONGRATULATIONS, you have simply passed chemical science 101. there'll be a pop quiz on Friday!


Aqua Regia
Aqua regia may be a terribly special case. this can be a mixture of focused acids, that isn't only a very robust acid, however is additionally a very robust oxidizer. it is capable of oxidizing gold to gold chloride, that is soluble in water. Yeah, I heard of it however wherever do i purchase it? You don’t compass, you make it. acid is nothing more than a mixture containing 3 parts of focused acid to one part of focused nitric acid. actually this universally used formula isn't quite correct. If you would like to make it right you mix nine parts of nitric to forty one parts of hydrochloric however the 3/1 formula is good enough for state work. this can be a rather dreaded chemical agent. If you're reaching to make/use it continually wear plastic gloves. sometime you will convey Pine Tree State for this recommendation.

Aqua regia dissolves gold and every one the noble metal metals terribly rapidly (especially if hot). it will additionally dissolve damn near the rest in your sample. Silver, iron, magnesium, manganese, aluminum, etc. if truth be told it will attack any metal. the stuff emits a red vapor that is terribly irritating. It’s nasty stuff and unless you really have to be compelled to use it, it is better to try to to the task another way.

If you dissolve gold in acid and wish to recover it you will find that you just must take away the nitric acid by evaporating the solution with heat. this can produce scores of the red vapor. you want to not let the solution go fully dry. Stop heating once you still have simply slightly liquid left. currently you want to add additional hydrochloric and repeat the procedure. Repeat this evaporation 3 times or till there are not any additional red fumes coming off. currently add hydrochloric so you have enough liquid to work with. All the metals will be in answer as their chloride salts. If you dilute this answer with Associate in Nursing equal volume of water you will in all probability get a white cloud of silver chloride that you'll be able to filter off. currently to recover you’re gold. in all probability the simplest is to cement it down by adding pieces of metallic element or atomic number 13. you will get a black-brown precipitate in the bottom that you just can smelt back to nice yellow gold. There square measure numerous different ways in which to recover the gold however that’s another page.

Things that you just can Use Acids and Bases For
Any robust acid will be used for cleansing ore or concentrates. However, there square measure reasons why you should use one or the other however not simply anyone. I cannot offer you a direction for cleansing gold bearing materials. It depends too much on what is in these materials that is making cleansing necessary. The one that I can tell you not to use is nitric. I know, lots of people use nitric to clean concentrates before amalgamating with mercury to recover the gold. they're actually losing some gold. How much, I can’t say. These of us can almost always say, "Im not losing any gold, gold does not dissolve in nitric acid". they're half- right. Gold does not dissolve in pure nitric. terribly fine gold can, however, dissolve in solutions of nitric acid containing chlorine. nearly all soil contains important quantities of chloride salts. once these salts square measure put into a robust acid answer, they "dissociate", that is if the salt was metallic element chloride it will forced an entry a metallic element ion and 2 chlorine ions. Take it without checking that the chlorine ion can currently pick up hydrogen from the water and currently becomes HCl, acid. OK, bear in mind however you make cobalt blue Regia? three parts hydrochloric and one half nitric. that will dissolve gold rapidly. You created sort of a "weak" acid. it is robust enough to dissolve terribly fine gold.

So, if you would like to clean concentrates DON’T use nitric till you have tried all the others first. it is the last resort. Best to undertake hydrochloric first. Don’t use focused acid. Use concerning 1-2 traditional. focused is twelve traditional, right? Dilute it with water 1/12 and you have one traditional acid etc. you should be shopping for your hydrochloric at the native ironmongery store as "muriatic acid". this can be six traditional acid. it's already been diluted 1/1 with water. therefore if you dilute muriatic 1/6 you will have one traditional acid. Yes, you'll be able to use sulphuric however commit it to memory is sort of nasty to work with. It tends to eat up your cloths etc. it is the most cost effective but. You see, the explanation {you square measure|you're} washing ore etc with acid is that there are salts in the material that interfere with recovering the gold with mercury or different. What you're trying to try to to is to make a salt of the acid you're washing with that can dissolve in the water so you'll be able to get eliminate it. the majority salts of hydrochloric (chlorides) square measure soluble in water. Sulfates (salts of sulfuric) don't seem to be all soluble. If you don’t convert Associate in Nursing insoluble salt to a soluble one, you probably haven’t helped matters any. So, strive hydrochloric first. the full idea is to convert insoluble salts into soluble salts (those that will dissolve in water) so they will poured off and discarded.

Sulfides
Although having nothing to try to to with acids and bases i feel it is so as to debate the matter of sulfides in your concentrates and ore. Since we have a tendency to square measure talking concerning cleansing of ores of unwanted or meddlesome salts we must always take into account the case of ores/concentrates that contain sulfides. Sulfides (salts of sulfur) square measure one amongst the most reasons why generally you just cant get the gold to amalgamate with mercury, dissolve in cyanide, or react to the other extraction method. Sulfides square measure terribly immune to chemical conversion to soluble salts. So, we have to try to to something totally different. an extra way to skin the cat. unfortunately we are going to have to be compelled to resort to heat. The time-honored way to take away sulfides from ore is solely to get it very hot.

The way to do that on a small scale is solely to get a bit of sheet metal. previous furrowed roofing, a bit of "valley tin", unspecified kind of thin steel. find many rocks or different equal put the metal on them. currently build a roaring hearth beneath. put your ore/concentrates on the metal.

Spread it out so it will heat rapidly and return to your camper for a chilly brew. once it starts to get hot, if sulfides square measure the matter, you will begin to smell sulfur, the odor of rotten eggs. will anyone however Pine Tree State bear in mind once you got a rotten egg once in awhile? If not, it’s the odor of a converter that isn’t operating good. Heat the ore/concentrates till the odor is no longer noticeable. Let it cool and give it a wash with one traditional hydrochloric followed by water. Your material ought to currently be pretty clean and amenable to merger or extraction by chemicals. this can be a way that has been used forever in areas wherever scores of sulfur was deposited with the gold. If sulfides square measure your drawback, try it, it works.

Dealing with black sand
Did you recognize that you just can dissolve black sand? actually, you don’t dissolve it you convert the iron compound to iron chloride and dissolve that so you'll be able to get rid of it going your gold behind. You see, making salts is important and to your advantage. this can be one amongst the cases wherever you will wish to uses focused acid. simply take your gold with the black sand and put it in a suitable container. A borosilicate (Pyrex or Kimax etc) glass container like a "beaker". Add focused acid. you will notice that the acid begins to show yellow. the color is as a result of the iron chloride that you just square measure making is yellow. currently this can be sort of a slow reaction therefore don’t get in a hurry. bear in mind what we have a tendency to aforementioned concerning reactions and temperature? If the reaction isn't going quick enough for you, simply warm the reaction till it is simply hot however don’t let it boil. it is additionally best not to use an oversized volume of acid. It’s far better to start out with a small quantity. once you suppose the reaction has stalled or stopped, pour off the acid and replace it with recent. there's an honest scientific reason for this however i really don’t suppose you would like to open that may of worms. If you heat this reaction make certain {you square measure|you're} out aspect or {in a|during a|in an exceedingly|in a terribly} well aerated house as a result of it is reaching to produce fumes of hydrogen chloride that are very irritating. You don’t wish them in the house.

Now, i know that you just square measure by currently a pretty good basement chemist and i don’t have to be compelled to tell you to wear gloves, do I? Do I??? If you forgot, head to beginning, go directly to beginning, don't pass precautions ---etc—etc. you have failing a pop quiz and will be penalised ten points and three burned fingers.