l3sk42 *zv.a v Frank Altmayer, CEF Pgt= Scientific Control Laboratories Inc. 3158 Kolin Avenue Chicago, IL 60623-4889 The Hunt for Quicksilver ur client received a violation for dis- ertyisthefactthatmercuryisametalthat The term "mad hatter," in the story 0charging an effluent containing too has some solubility in water (about 20 Alice In Wonderland, was not based to- much mercury. Because he was not ppb,at2OoC).IfmercurymetalisaIlowed tally in fiction. Felt production in the 1700s aware of any process within his facility to flow into a piping system, it may then utilized mercurylmercury compounds. that used mercury-containing com- reside for a long time, slowly dissolving "Hatters" were well known to have the pounds, our assignment was to track into the water and releasing excessive occupational hazard of going "mad," al- down the source of the mercury and concentrations into the discharge. though the medical profession was not eliminate it, ortreat theeffluent in orderto Common mercury compounds that aware that mercury was the cause. Mer- return tocompliance.Thisalsogave us a have been used in metal finishing include cury guilders also suffered nervous chance to look into the role of mercury in mercuric chloride, sulfate, nitrate, cya- traumaandeventualdeath, at earlyages. metal finishing in greater detail. nide, oxide and dichromate. Processes The prime route of entry was-and is Mercury-aka "quicksilver," aka that include mercury-containing com- today-inhalation of the vapors. Mercury "hydrargyrum (Hg)"-xcurs naturally in pound arezinc-mercury plating (we hope, and some of its compounds can also be a free state, or mixed into its ores. The no longer out there), and steel coloring absorbed through the skin, and it can be principal ore is cinnabar, which is mined solutions. Because mercury is present as ingested. in numerous countries, including Spain a residual from one means of the produc- Acute symptoms of exposure include (Iberia),Austria, Canada, Mexico, China, tion of sodium hydroxide, there is a pos- burning mouthlthroat, thirst, shock, car- Chile, and Japan. In the US., the states sibility that excessive mercury may be diac arrhythmia, nausea, vomiting, ab- of California, Oregon, Nevada and Wash- present in any metal finishing process dominal pain. bloody diarrhea, eyedam- ingtonare our principal sourcesofcinna- that contains "mercury cell" sodium hy- age upon contact and a metallic cast to bar. Simply heating the ore beyond 500 droxide, including waste treatment. skinleves, "C will distill off the mercury as a vapor that can then be condensed, to yield pseudo silver-likemetal that is an elusive liquid at room temperature. Two Methods of NaOH Production Mercuryisverydense (13.5gramsper 1. Diaphragm Cell cc) and does not readily react with non- 2. Mercury Cell oxidizing acids. It is a true metal, con- - ducting electricity and existing in monova- + lent and divalent states. It readily forms solid solutionswith numerousothermet- als, which are referred to ai "amal- gams." Chances are that the fillings in your teeth contain a mercury amalgam with silver, for example. Other amal- gams are formed with copper, nickel and gold; but not iron, which is some- times used for mercury containers. Major uses for mercury and mercury compounds include dental fillings, bat- teries, feltmaking, thermometers, red pig- ments (vermilion), mercury vapor lamps, medicines,silent electrical (wall) switches, barometers and in semiconductor de- vices. A unique properly of this liquid metal is its ease of vaporization. Simply Mercury-Sodium Amalgam exposing the metal to air, or blowing air through it, will vaporize the metal into a toxicgaseous state. Another unique prop- oduclioo of NaOH using 8 mercury cell. January 1993 35 Chronic exposure symptoms include contain more than 0.030 mgiL of mer- tions, it may mean removing the asuoci- muscleweakness, sore mouth, anorexia, cury. While the metal finishing industry ated plumbing that had h'ddled th,e fever, nausea, abdominal pain, vomiting, has no federal categorical standards on rinsewater from such an operation. ., diarrhea, headache, neivous disorders, mercury in the wastewater discharges, Because mercury is regulated to such kidneylliver dysfunction, hand tremors, mercury is typically regulated on a local low concentrations, chemical purity be- insomnia, loss of memory, loosening of level, at extremely low concentrations- comes a significant issue. Prime sus- teeth and excessive salivation. There typically from 0.1 ppb to 0.5 ppb. Typical pects for mercury contamination are so- is some evidence that mercurylmer- mercury compounds that may have been dium hydroxide, sulfuric acid, and color cury compounds may be carcinogenic used in metal finishing processes in the dyes used in anodizing (especially red and teratogens (linked to birth defects). past are: ones). The vast majority of metal finish- Mercury is a protoplasmic poison. After ing processing solutions contain sodium exposure, it circulates in the blood and Mercuric Nitrafe hydroxide, so it becomes the prime sus- is stored in the liver, kidneys, spleen This mercury compound is a white, deli- pect in a mercury hunt. and bone. quescentpowder. It is apowerful oxidizer How does mercury get into sodium Skincontactwithsoluble mercurycom- that can form explosives with acetylene, hydroxide?Sodium hydroxideis produced pounds can result in severe corrosive ethanol, cyanide and sulfur. It decom- primarily in two ways: A diaphragm cell, effects. Some mercury compounds cre- poses upon heating, to yield elemental and in the mercury cell. (See Fig.) The ate toxic mercury vapors. mercury and toxic oxides of nitrogen. mercury cell consists of two plating com- Mercury and its compounds are regu- Typical usesinclude blueing andcoloring partments. In the first compartment, a lated under OSHA, RCRA and SARA. of steel, and as a sensitive analytical graphite anode is used to "p1ate"sodium OSHA PELsare: 0.05 mglcubicmeterfor method for the determination of traces of onto a mercury cathode out of a brine. mercury vapor, 0.01 mglcubic meter for chloride in acidic solutions by titration. The mercury-sodium amalgam is then alkyl organic mercurial compounds, and used as an anode to plate sodium out of 0.1 0 mglcubic meter for aryl organic and Mercuric Chloride the mercury amalgam and into a water inorganiccompounds. Under RCRA regu- This is a white, crystalline material or solution, which then becomes a sodium lation, D-009 waste that contains more powder that becomes volatile to a toxic hydroxide solution. The sodium hydrox- than 16 mg/Kg mercury must be sent for vapor at 136 "C,and decomposes to ide solution can become asconcentrated recycle. Waste that contains less than 16 elemental mercury upon further heating. as 70 percent, using this method of pro- mglKg must be treated to aTCLP level of This compound is considered teratoge- duction. Unfortunately, the sodium hy- 0.025 mglL. D-009 wastewater must not nic. Mercuricchloride is included in some droxide is contaminated with as much as formulations for the coloring of ferrous 1,000 ppb or more of mercury. Thus, alloys and in the old zinc-mercury alloy mercury cell sodium hydroxide, has no plating process. place in a metal finishing shop. The mercury you may find in sulfuric Mercuric Oxide acid, dyes or other chemical products This is a bright orange-red powder that generally does not come from any pro- was used for red paint pigments at one duction method. It's simply there as a time. It is a powerful oxidizer that can chemical impurity. readily explode upon mixture with reduc- ing agents, phosphorus, sulfur, or mag- On the Hunt nesium. Mercuric oxide reacts violently Ifyou are on a mercury hunt, the first step with peroxide and ethanol. Heating mer- is to contact each chemical supplier you curic oxide creates toxic mercury fumes. use, and request a mercury analysis of Past uses of this compound include a the productorcertification that theprod- "mercury dip," to promote adhesion of uct is mercury-free. This may not nec- plated deposits on tellurium-copper al- essarily allow you to eliminate all mer- loys and as an alternate source of mer- cury sources. cury ions for zinc-mercury plating. You may still need to analyze various Zinc-mercury alloy plating was per- #astewaterstreams for mercury, in order formedearlyin thiscentury,inanattempt to isolate specific sources. There is no to obtain a more pleasing 'White" zinc "quick-and-dirty"testto detectafew ppbs deposit. The bath contained zinc cya- of mercury, so you will need a laboratory, nide, sodium cyanide, sodium hydroxide, equipped with a cold vapor atomic ab- and mercuricchlorideoroxide(0.25g/L). sorption spectrophotometer. One analy- This bath contained about 50,000 times sis typically costs $25, so choose your the amount of mercury now allowed in the suspects wisely, concentrating on pro- plant wastewater discharge. The anodes zesses that contain sodium hydroxide were zinc, containing 0.5-1 percent mer- and sulfuric acid. cury. Needless to say, we doubt if this The keys to compliance with mercury process is in use today. However, if you jischarge limitations are detection and are aware that your facility may have alimination, as opposed to treatment. If used this process (or any mercury-con- you find achemicalsolution thatcontains taining process) in the past, and are a significant amount of mercury, contact Free Details: Circle 115 on postpaid reader S~NICS card. having adifficult time with mercuryviola- ihe supplier for an alternate material. 36 Plating and Surface Finishing I the ass'o Change suppliers, if necessary. ~ttiei andwith mercury. Empioyeesshouldtakc 4. The discharger has an inspection andled t 1 aciions to eliminate mercury from you, a daily shower and clothing change program likely to reduce or to prevent an !ration: , facility: Workersshouid haveanannual(orm0re- increase in the ievei of mercury ftedto su' I Fliminate the use of mercury-contain. frequent)physical exam and blood/urine discharges. U I purity b ing thermometers test for mercury.