TerraFlow solves heat challenge
“We’ve had an upward trend in compression strength over the past few months due to Terraflow™, and the increase in strength will allow a decrease in binder cost over time.”
The Lucky Friday Mine is a deep underground silver, lead and zinc mine located in the Coeur d’Alene Mining District of northern Idaho. In mid 2014, Hecla Mining asked Lafarge to provide alternative backfill solutions as the Type I Portland Cement it was using had become problematic at deeper levels. Mid 2014, Lafarge’s Terraflow75™ tests on the mine tailings proved successful and Lafarge began supplying regularly to Lucky Friday Mine in 2015. By using Terraflow75™, Hecla Mining was able to efficiently deploy the paste backfill while maintaining the desired strength gain properties.
Since 2011, Lafarge has been supplying Type I Portland cement and fly ash to Hecla Mining for the sinking of the #4 shaft and also secured supply of Type I Portland cement for mine paste fill operations. As deeper elevations were being reached at Lucky Friday mine, the Type I cement caused the backfill to solidify prematurely due to high heat. This made it difficult to place the paste fill and Hecla Mining contacted Lafarge for possible alternatives.
“TerraFlow™ will work great to allow us to mine and fill stops at greater depths.”
Tyler Emery, Mine Engineer – Hecla Mining Company
Mid 2014, Lafarge began testing Lucky Friday’s mine tailings with Terraflow75™, a specialized blend of cementitious and other construction materials. Tests included preliminary paste fill testing, flexural testing and Modulus of Elasticity (EMOD) testing. Testing showed that TerraFlow75™ held its workability for an extended period of time and had comparable strengths to pure Portland cement.
Regular shipments to Lucky Friday Mine began in 2015 after lab tests were conducted and the results were successful. Hecla Mining is making significant cost savings by using Terraflow75™, while maintaining the efficiency and quality of their backfill operations. Says Tyler Emery, Mine Engineer at Hecla: “erraflow™ poured nicely, didn’t stack at all and they even trimmed the water back on the second pour because they thought it was too ‘soupy’. I was able to core the top of the second pour and got compressive strengths averaging 510psi (uncorrected) at 14 days, and 14 day lab cylinders at 580psi. Terraflow™ will work great to allow us to mine and fill stops at greater depths.”