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Tellurium Recovery during Dore Processing

Tellurium metallurgical behaviour

The metallurgical behaviour of Tellurium is close to Precious Metals:

  • During Base Metals Processing, Tellurium is extracted together with Precious Metals

  • During Precious Metals Concentration Processes, Tellurium is collected together with Precious Metals

The price of Tellurium can get close to the price of Silver

  • Silver : $ 30/ to (November 2024) = $ 1,000 / kg

  • Tellurium November 2024 : $ 80 / kg

Tellurium December 2011 : $ 300 / kg

Tellurium occurrence in Precious Metals By Products

Tellurium is an impurity in Precious Metals Concentrates :

  • In the Silver Alloy extracted from Lead Refining

  • In Anode Slimes produced during Copper Electrorefining

Tellurium occurrence in Precious Metals Operations

Tellurium is an impurity during Precious Metals Processing :

  • Tellurium is perturbing the PM recovery.

  • Tellurium is accumulating in By Products of the PM process.

  • Tellurium is increasing PM operating costs :

  • increased volume of By Products

  • increased charges for the Re-processing

  • increased PM loss in By Products

Recovering Tellurium makes sense

  • A Tellurium activity of 10t / year is common in many Precious Metals Operations

  • Extracting Tellurium will result in :

  • Reduced PM losses and processing costs

  • Potential additional gross value corresponding to 10t Tellurium : 0.8 million $ at current market prices (November 2024)

  • The cost for recovering Tellurium is limited :

  • No investment needed, use of existing equipment

  • No additional charges except assaying

Poor selectivity of direct Extraction

  • The selectivity of Tellurium extraction from Precious Metals By Products is poor, due to :

  • Low Tellurium content

  • Complexity of the materials

  • Presence of other metals with similar metallurgical properties

  • Tellurium recovery rates in direct extraction processes are not optimal

Tellurium Concentration before Extraction is preferable

  • Tellurium concentration allows to :

 

  • Increase Tellurium content and metallurgical activity

  • Reduce impurities, in number and content

  • Reduce complexity and increase predictability and reproductibility of process results

  • Tellurium recovery rates after concentration are

  • Improved

Preliminary Tellurium Concentration prior to Extraction

  • During Precious Metals Processing, Tellurium can accumulate in the Furnace together with Silver, thanks to :

  • Use of correct oxygen potential in the Furnace

  • Adjusted slag composition

  • Use of other metals, Copper, Lead, Silver to collect Tellurium as Telluride (Cu2Te and similar)

Controled Tellurium Extraction during Silver Refining

  • The Silver Refining Process must be monitored in order to identify the several Refining Steps :

  • Adjusting oxygen potential of the Furnace

  • Controling of the slag fluidity

  • Monitoring of the slag composition

  • As a result, Tellurium will concentrate in the Refining Slag with contents between 5% and > 15%, depending on the Tellurium activity

Conclusions

  • Check the Tellurium activity in your Precious Metals Operations :

  • Determine the Tellurium content of Input and By Products

  • Establish a Tellurium Mass Balance

  • If Tellurium is confirmed then it makes sense to look at extracting Tellurium and producing a Tellurium By Product

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