Chemistry of Gold: The Ultimate Guide to Smelting Gold & Silver

⚒️ Chemistry of Gold: The Ultimate Guide to Fire Assaying In today's video, we are getting technical. We’re moving beyond simple panning and diving deep into the fire assaying process to determine exactly how much gold and silver are hiding in a batch of high-grade concentrates. We cover everything from custom flux recipes to the complex chemistry that happens inside a red-hot crucible. If you’ve ever wondered how the pros separate the "treasure from the trash" using fire and iron, this one is for you. 🧪 The High-Sulfide Flux Recipe Dealing with high-grade concentrates (sulfides and oxides) requires a different approach than standard head-ore samples. Here is my go-to recipe for a 100g sample: Soda Ash - 100g - Basic flux; absorbs sulfides and converts them to soluble forms. Anhydrous Borax - 65g - Acidic flux; dissolves silica and metallic oxides. Silica Sand - 35g - Acidic flux; protects the crucible and absorbs oxides. Bismuth Oxide - 30g - The non-toxic collector metal that "rains" down and grabs the gold. Potassium Nitrate - 15g - A powerful oxidizer to drive off sulfur. ⚗️ The Science of the Smelt We break down the "nuts and bolts" of the reactions taking place in the furnace. To prevent a matte layer (a failed smelt that traps your gold), we use iron nails to rob the sulfur from the less reactive metals. FeS2 + Fe → 2FeS The 2FeS becomes soluble in our slag, leaving the precious metals to settle safely into the bismuth button at the bottom. We also look at how Soda Ash breaks down: Na2CO3→Na2O + CO2 ​ Trial & Error: Dealing with the "Matte" It doesn't always go perfectly! In our first run, we ended up with a thick matte layer—essentially a failed smelt. We troubleshoot the process by halving the concentrate-to-flux ratio, ensuring we have enough "chemical horsepower" to absorb all the impurities. The Results: Run 1 (Matte issues): ~120 g/t Gold & Silver. Run 2 (Clean Smelt): ~180 g/t Gold & Silver. While 180 g/t is a great paycheck, for these high-grade cons, we’re looking for kilograms per ton to really make it worth the effort. For more info please email or call: Email: info@MBMMLLC.com Phone: 360-595-4445 Website: http://www.mbmmllc.com/ Patreon: http://www.patreon.com/MBMMLLC Facebook: https://www.facebook.com/MBMMLLC Instagram: https://www.instagram.com/mbmmllc/ Twitter: https://twitter.com/MBMMLLC ⏱️ Video Timestamps: 0:00 – Intro: Fire Assaying High-Grade Concentrates 1:45 – The 3 Main Flux Components 3:30 – Why Bismuth is better than Lead 5:10 – Technical Breakdown: The Chemistry of Iron Nails 8:45 – Loading the Crucible: Avoiding the "Boil Over" 11:20 – The Pour: Identifying a Failed Matte Layer 14:00 – Cupellation: The Magic of the Bone Ash Sponge 16:30 – Trial 2: Adjusting the Recipe for Success 19:00 – Final Weigh-in and Grams per Ton Math 21:15 – Sneak Peek: Reprocessing 1,000s of lbs of Slag! Enjoyed the deep dive? Hit that SUBSCRIBE button so you don't miss our upcoming video where we re-smelt all my old slag to see how much gold I’ve been leaving behind! #GoldMining #FireAssay #Chemistry #GoldRecovery #Bismuth #Smelting #MBMMLLC #Geology