Bromine Production Overview

most of South Arkansas is covered with trees except for the parts of it that are underwater so it may be a bit surprising to discover that lurking in this forest is a major chemical enterprise just a few steps from here is a plant owned and operated by Great Lakes solutions part of the kimchi Recor / Asian this plant behind me and the other ones like it scattered over about 500 square miles of South Arkansas produce about half of the world's supply of an element that element is bromine bromine is one of the elements of course but more specifically it's one of the halogens right below chlorine and right above iodine now bromine as one of the elements has its own unique chemistry but maybe bro means more unique than most it's one of the few elements that's liquid under standard conditions but it's the only element that's a liquid that isn't a metal bromine has a lot of other interesting chemistry that we're going to explore in other videos but today we're going to concentrate on understanding how elemental bromine BR 2 is made here in this plant I talked with Patti Cardin and Jeremy Pratt of Great Lakes to find out why they are making bromine in South Arkansas actually the reason why our facilities are here in South Arkansas it's pretty unique there is a natural resource that say Brian reserved over seven thousand feet beneath our feet right now if you look closely you can see it's a very porous rock the formation is known as the smack over limestone formation and the brown water is trapped in this rock so I got a big limestone sponge full of salt water with a lot of bromide in it about a mile and a half down and this pipeline here as that salt water in it and it's not exactly hot but it's definitely uncomfortably warm the brine is actually close to 200 degrees Fahrenheit when it comes out of the reserve and when it makes its way into the plant the process so joining us here is John Thomas one of the operators at Great Lakes south plant now John has been an operator here for I'm told for about five years so he knows a thing or two about making bromine so John there's some pretty big pipes written in this reactor over here how much Brian are you guys using we use about 3,500 gallons a minute get the brine here and you're good to go or no we actually use the rate strippers to removing the h2s or natural gas to slip into Bronto what's the problem with those two things when you get rid of them h2s will actually hurt us by fouling our packing our Tower and is hurting the efficiency it also forms which we have to treat before dispose of in the tail branches for natural gas it caused a problem no natural gas actually hilts us we actually send all of our natural gas by all three fields to line old lion old processes sulfur out of it and sends the sweet gas back to us to burning or more it so once you get rid of the h2s and you get rid of the natural gas are you good to go we are we are so you bring it in and where does it happen to bring it in right over here great can we go take a look at that absolutely grab your heart your safety glasses we will take a look safety at plants like these is serious business the crew and I had to get training before we can even come into the plant and there are safety notices and warning signs everywhere so this big orange pipe is the brine coming into the reactor we add we bring flooring in as a liquid it takes roughly ten seconds for it to get to 100 feet to the top of the tower for the chlorine and bromine reaction is taking place as it goes all the way to the top of the top this whole process works for two reasons the first chlorine has a higher affinity for electrons than bromine does it's more reactive the elemental chlorine takes electrons from the bromide chlorine oxidizes the bromide turning you the end to bromine and the chlorine is converted reduced in chemical terms into chloride think of it as chlorine muggin the weaker bromide for its electrons if you will an equally important component but perhaps not so obvious is the fact that chloride has a higher affinity for water than bromide does we make more chloride and it's higher affinity for water provides an important driving force moving the reaction Ford Jeremy told us that the bromide and chlorine solution takes about 10 seconds to travel up the orange pipe to the top of the tower chlorine is so reactive that 10 seconds is more than enough time for the chlorine to turn the bromide in the feed brine into elemental bromine by the time it gets to the top we've got a solution with a little bit of elemental bromine a lot of table salt and a few other minerals next we need to separate the bromine from the rest of the solution with our earplugs securely in place we climb all the way to the top of the tower where Jeremy explains how that separation is accomplished at least he tried to tell me maybe if we go back down a few levels we can hear what he's trying to tell us that was actually the scene being ejected into the back of town well we actually use feed and inject get across the converging diverging nozzle and we use the Bernoulli equation whoa how do we get into a discussion about physics the show is chemistry at work not physics at work so skip ahead I guess the key thing here is that you're checking steam is dropping the pressure and raising the temperature at the same time that's the woodsy the bread is about a hundred and eighty degrees Fahrenheit when it gets the vacuum out and it's about a half an atmosphere so the bromine actually flashes out of the branches they pull most of the bromine out of the solution by boiling it out under reduced pressure now reduce pressure helps things to boil but you still need heat to convert a liquid into a gas whether the liquid you were boiling is something exotic like bromine or as mundane as water so it turns out they don't just insulate those pipes holding the feed brine to keep absent-minded professors from burning themselves remember the solution comes out of the ground at about 200 degrees Fahrenheit 93 degrees Celsius just under boiling the insulated pipes prevent heat loss as the feed brine travels from underground wells to the plant heat they're going to need to boil the bromine which cuts down on production costs now they add the chlorine to the hot brine as it travels up the tower where steam is injected and a vacuum is created one of the important tricks in this process is to not reduce the pressure so much or to get the temperature so high that too much of the water that's dissolving all that salt evaporates along with the bromine at one atmosphere of pressure bromine boils at fifty eight point eight degrees Celsius just under one hundred and thirty-eight degrees Fahrenheit wait a second 180 degrees and half an atmosphere that's a lot more than the hundred and thirty-eight degrees needed to boil bromine at one atmosphere it seems like massive overkill so the bromine actually flashes that automatically flash that's the key word they want this done fast thirty five hundred gallons a minute are being processed through this thing that's more than this 55-gallon drum every second they don't have time to mess around high temperature and low pressure help get most of the bromine converted to a gas very quickly but even so there are still some bromine that's left in the solution that's now falling down inside the bromine tower to make sure all the bromine is separated all of the bromine paper no matter where it's formed in the tower moves up to the top of the tower and that bromine gas is then pulled off and sent to a condenser that's just cold enough to remove most of the water vapor that comes along for the ride the bromine vapor is then sent to a second colder condenser that converts the bromine itself into a liquid now that liquid bromine still has a little bit of chlorine water and a few other contaminants so the liquid is then sent through a drying process that removes almost all of this trace contamination once the bromine is produced they load it into tanker trucks or rail cars to send out to customers but a lot of this bromine gets used right here on this site after the bromine is extracted from the brine any contaminants like chlorine or acid in the solution or taken care of and the leftover tail brine as they call it is put back into the same rock formation it came out of but using a well far away from the well used to supply the plant elemental bromine isn't something you go down to the store to buy and bromine isn't in a lot of the products you buy but it contributes at least indirectly into things that you do care a lot about for example materials made from elemental bromine are used to control mercury pollution from coal-fired power plants bro means also use to make the materials that make up the very dense salt solutions that are needed to drill high-pressure oil wells you can find bromine and hydrobromic acid and intermediates used to synthesize pharmaceuticals and you can even find bromine occasionally in final products that you do buy such as drugs or pesticides but the most important use for bromine is almost certainly flame retardants and you do buy flame retard whether you know it or not there's a lot of bromine used in the plastics you see in everyday products you're watching this video on a monitor or screen right now and the chances are very good that the plastic and that device contains a bromine product made right here in this plant the upholstery and padding and the cherry you were sitting on probably have similar bromine containing materials in them the purpose of these organo bromides is to make it harder for flammable materials to burn a very important use so you're pumping the bromine up out of the ground here the brine comes into the plant then over here you're taking that brian without the bromine and pumping it back into the ground it makes a big circle under our feet exactly thanks so much for showing us around today Jeremy this has been really fascinating learning how you guys make bromine please check out all of our other videos where we look at the details behind various aspects of this process either on youtube or on our website again thanks for watching chemistry at work thanks so much there really you