Mercury Retort Training In Kakamega

On an annual basis, 37% (1600 tonnes) of global mercury emissions are linked to ASGM, causing harm to miners and the wider environment. Mercury is mixed with crushed ore, which attracts gold particles to form a hard amalgam. This is then burned, releasing mercury vapour into the atmosphere and leaving gold for sale.

Earlier this year, the Impact Facility – in partnership with Makal Jewellery – were able to fabricate eight mercury retorts, as part of efforts to reduce the environmental and health footprint of small-scale mining. This equipment helps to reduce mercury emission during the amalgam burning process, by containing and recycling vapour and mercury fluid in a closed cylinder.

Figure 1 The Fabricated Piece of mercury retort, Crucial areas fabricated with stainless steel

Preparing for the Training

The fabrication process of retorts took one month, including designs, material sourcing and delivery to Kakamega county, Kenya, in advance of trainings.

During this period, the Impact Facility embarked on preparation for training materials, learning from best practice approaches successfully deployed elsewhere.

Although, mercury retorts have been in use for decades the adoption of this safer burning method has had more than its fair share of its challenges.

In the case of our work, these included  low levels of understanding regarding the health impacts of mercury amongst miners as well as a required period of trust building towards the use of mercury retort equipment, which only 10% of the miners had heard of and were familiar with.

We also had to test the right materials for the retort as miners feel that burning amalgam with some metals discolours the gold and loses the coveted grade by the gold buyers.

Training Week, Local Travels Opened

In August 2020, the Kenyan Ministry of Health announced that the nation had started to flatten the pandemic curve, and the infection rate had significantly gone low. Following this change, intercounty movement opened up and it became possible for trainings in Kakamega to begin, using the retorts.

Prior to trainings rolling out, the Impact Facility attended a workshop launch for the Kakamega County ASM committee; the first to be gazetted in the country. This committee will be instrumental in formalizing mining groups, issuing and revoking permits and capacity building miners in a range of areas, including in relation to mercury hazards.

The Impact Facility presented work which has been supported to date in the region and how the partnership with the committee can help to build a resilient mining community in the region through technical programs.

Mwangaza Mining Group Training

On the morning of 2nd Oct 2020, the Impact Facility gathered a group of 10 miners from Mwangaza mine group led by Mr Justus Khakabo. The group comprised of six men and four women who gathered to witness this important equipment that would help the miners live longer when used often.

Figure 2 Mwangaza Miners carefully study the mercury retort before experimenting began

A dialogue session was facilitated with miners to discuss their understanding of mercury, including its benefits as well as harmful effects.

A theory training in front of the retort system then followed, with the miners helping in assembling the mercury retort system.

The process for preparing the new equipment then began; including an initial heating phase of the stainless-steel metal tubing, to free any inclusion in it that might interfere with the Gold.  

The trainer demonstrated every important area of the retort, highlighting the areas that would need water for cooling the hot mercury vapour, how to effectively apply heat in the cap for thorough roasting of the amalgam and ensuring that the end of the tube is connected with water container to collect the condensed mercury.

Demonstration Process

Once the preparation phase was complete, the mine leaders selected one of their mine gold washers to offer an amalgam sample for burning. The selected miner, Margret, who is a member of Mwangaza Mining group, had just recovered half a gram of gold amalgam through sluicing, and she was excited to be the first to try roasting it with the mercury retort.

The miners carefully placed the amalgam in the cap and closed the lid ready to burn, the timer was set for 5 min, and heat applied.

Figure 3 0.5gms Gold amalgam before…
and after burning with the mercury retort

Once the heating process was complete, what came out was entirely yellow, gold-sponge;  free of mercury – with the silvery mercury having evaporated to the top of the tube. The miners were mesmerized to see that the amalgam had obtained a better colour than the one they usually achieve when they use open burning process.

Margret, the owner of the amalgam, was seen receiving her roasted gold, and she was also happy to be interviewed on the new experience and as a first-time user of the retort in Mwangaza mine.

The Mine leaders received the retort system on behalf of the mine; they promised to start using the retort as well as signed a document of commitment and acknowledgement to be in possession of the equipment

Shirumba, Jasho and Ingughu Mining Groups Combined

On the second day, there was a need to combine three mine groups and meet in one central area and in this case, at Shirumba Mine group. The total number of attendants were 15 miners: eight women and seven men.

Figure 5 Retort training in Shirumba mining Group together with Jasho and Inghuhu Mines

The Impact Facility’s trainer gathered the miners together and again explained to them how the retort worked. The trainer received around 5gms of amalgam to be roasted; it was split into two halves before each were placed inside the retort burning cup for heating.

The timer was set for ten minutes while the trainer continued to explain the importance of the retort in recovering mercury.

After 10 minutes the cup was opened, but the mercury had not fully been freed, and therefore there was a need to burn for some more minutes, it was observed that the samples took 15 minutes in total to achieve a yellow colour that is recommended by the gold buyers.

Figure 6 5gms Gold amalgam before…
and after burning with Mercury retort

The trainer explained that the bigger the amalgam, the more time is taken to completely free the mercury and the vice versa, he also highlighted that the miners needed to use the retorts more often to ensure that mercury coated effectively on the tube before it starts to condense back for recovery. After the training demonstration, each of the mine groups was handed over the mercury retort system for permanent use.

Figure 7 Burned amalgam in the a gold trader’s Office ready for sale

Lesson Learnt

Gold trader Need for the Mercury Retort more than the Miners

During the training, it was noted that among the attendants were gold buyers who are key people during the burning of amalgam; Gold buyers shy away from buying an already roasted amalgam and therefore, they were keen to understand how the mercury retort works.

The future strategy would be to ensure that Gold buyers own a mercury retort in their buying offices, which will help propagate good burning practice.

Need for the miners to use the retort often to understand working parameters.

We believe that the use of retort is not a plug and play; a lot of discipline will be needed by the miners to ensure consistent use of the retort in their day to day affair.

Through Monitoring and evaluation, we believe the miners can feel accountable and ensure that their members embrace the method.

Furthermore, the mine groups that received the retorts also signed a commitment note saying that they will use the retort as often as possible and therefore, we believe that through the consistent use of the equipment will bring a positive change not only to the Miners but also the entire ASM community.

To learn more about how we manufactured the retorts, have a look Cyrus’ previous blog.