complex copper concentrates

Copper concentrates come in two “flavours” – Clean and Complex.

Clean copper concentrates have more than 20% copper and possibly gold and silver and low levels of the deleterious elements As, As, Bi, Cd, Cl, F, Pb, Hg, U and Zn. In addition, asbestos (referred to as fibre) is present in a small number of mine product streams. The Complex Concentrates have high levels of one or more deleterious elements. Each of the deleterious elements will have a threshold level in the offtake contract where the smelter will charge a penalty in addition to the treatment and refining charges. The penalty accommodates the increased costs of disposal and safe disposal.

Typical copper concentrate penalties.  Courtesy, AME Group
Typical copper concentrate penalties. Courtesy, AME Group

There is frequently an upper limit for some deleterious elements, above which the smelter may refuse to accept the concentrate. 

The most common deleterious element in copper concentrates is arsenic. Globally 65% of copper concentrates have less than 0.1% As. Above 0.2% arsenic, copper concentrates are considered to be Complex Concentrates and will be charged penalties. In the last decade, as new mine copper production has slowed the quantities of Complex Concentrates entering the market increased significantly while smelter capacity for these concentrates has declined.

Complex concentrates from Marcapunta in Peru (8% As), Chelopeche in Bulgaria (6% As) and Chuquicamata in Chile (1.2% As) have been the main producers. They have been joined more recently by production form Toromocho in Peru (1% As) and Ministro Hales in Chile (4% As).

Smelting Treatment Options

Prior to the 1990s there were many smelters that would accept copper concentrates with high deleterious element concentrations. However due to environmental concerns, liability concerns, tightening regulations and smelter closures at La Oroya in Peru, San Luis de Potosi in Mexico, Tacoma in the USA, Rönnskär in Sweden, PASAR in the Philippines and Kosaka in Japan, the number of smelters that will now regularly accept Complex Concentrates has declined very significantly.
Smelters that will now accept Complex Concentrates include Tsumeb in Namibia, Altonorte in Chile, Guixi in China and Horne in Canada. For complex concentrates that contain more than 1% arsenic, the Dundee Precious Metals smelter in Namibia at Tsumeb is now the only smelting option.

Altonorte is a custom copper smelting operation located near the port of Antofagasta in northern Chile. The smelter has the capacity to process 1,160,000 tonnes of copper concentrate per year. This operation is supplied with copper concentrates by third parties
Altonorte is a custom copper smelting operation located near the port of Antofagasta in northern Chile. The smelter has the capacity to process 1,160,000 tonnes of copper concentrate per year. This operation is supplied with copper concentrates by third parties

Most of the smelters which would previously accept high arsenic concentrates utilised roasters to fume of the Arsenic to produce arsenic trioxide (for which there is a limited market) and calcined copper with much reduce arsenic levels. Only Tsumeb still operates such a process facility.

Codelco installed an Outotec Partial Roaster (a fluid bed roaster) at its Ministro Hales mine
Codelco installed an Outotec Partial Roaster (a fluid bed roaster) at its Ministro Hales mine

Codelco installed an Outotec Partial Roaster (a fluid bed roaster) at its Ministro Hales mine in 2013 to reduce the as content of the copper concentrates. It is located close to Codelco’s Radomiro Tomic and Chuquicamata operations. Initially the project comprised an open pit mine, a 50 kt/d mill to produce 163 kt/a Cu and 287 t/a silver over a 14-year mine life. The ore contains a significant amount of arsenic (around 1.6-1.9% As) that results in production of concentrate with arsenic content just above 4%. To reduce the arsenic levels, a 550 kt/a fluid-bed roaster was constructed to safely process copper concentrate and recover arsenic for further confinement. In addition to calcine and sulphuric acid, the roaster produces flue dust (around 4% volume) containing 22% Cu.

Hydrometallurgical Treatment Options

There are a number of hydro-metallurgical treatment options (few of which have achieved commercial success) which do not involve roasting where the objective is to produce a residue containing arsenic in a form which is stable within a tailings dam. These process routes include atmospheric leaching, bio-oxidation and pressure leaching. Dundee Precious Metals prior to its acquisition of the Tsumeb smelter had attempted to permit a pressure oxidation circuit at its Chelopeche mine in Bulgaria but faced opposition for the usual socialist “ecological” groups.

Chelopeche Mine, Bulgaria
Chelopeche Mine, Bulgaria

Teck Aurubis have trialled their proprietary high pressure oxidation technology, CESL, on concentrates with up to 10% arsenic and report greater than 99% deportment of arsenic to leach residues.  Arsenic components in the residue have been identified as ferric arsenate and scorodite – both of which are considered the most stable forms for arsenic fixation. Teck Aurbis have achieved >97% copper and >90% Au and Ag recovery, LME grade copper cathode and gold and silver Dore production.

CESL residue stability test Courtesy: Teck Aurbis
CESL residue stability test Courtesy: Teck Aurbis

Blending Options

Due to the limited capacity and high costs of the smelters capable of accepting high arsenic concentrate, blending of clean and complex concentrates to produce a product that is below the smelter deleterious element thresholds has become a significant business opportunity. Generally, this is below the 0.5% Chinese threshold and the main blended concentrate target is Chinese smelters.

In 2014 Codelco set up a strategic alliance with Ocean Partners to blend high-As copper concentrate from its Ministro Hales mine with clean third-party concentrate bought in by both companies, at Ocean Partners’ concentrate blending facility in Taiwan.

In the near term it appears likely that the percentage of concentrates subject to arsenic penalties will increase, as will the percentage of Complex Concentrates in the market. In response to this Glencore has opened a new copper concentrate blending facility in Taiwan and a number of Chinese smelters are looking at locating blending and scrap processing operations in the region.

copper concentrate markets surprise

While copper futures trade in largely directionless, trading in a tight range there has been considerable action in the concentrate markets.

Reuters reports that the 10-member China Smelters Purchase Team (CSPT) has set treatment and refining charges at $55.00 per tonne and 5.5 cents per lb respectively for third-quarter deliveries. This is a significant move down from $92 and 9.2 cents in Q1 2019. This suggests considerable tightness on the copper concentrate supply side and could spell some grief and likely closures for higher cost smelters.

According to the International Copper Study Group (ICSG)  the issues with the supply side are the dearth of new mine production combined with lower head grades in Chile and markedly lower output at Grasberg where the operation is in the process of transition from open pit to underground.

Mine Production

ICSG in its latest study concludes that world mine production declined by about 1% in the first four month of 2019, with concentrate production declining by 0.5% and solvent extraction-electrowinning (SXEW) by 2.5%:ICSG in its latest study concludes that:

  • What little growth there was during the period was offset by declines in Chile and Indonesia;
  • Chilean production declined by 3.2% due to lower head grades;
  • Indonesian concentrate production declined by a massive 50% due to a transition from open pit to underground operations are the Freeport McMoran operations in Irian Jaya;
  • While DRC and Zambian production staged significant 11% production growth in 2018, production in the reporting period only managed 2.8%;
  • Production in Peru, Australia, China and Mongolia increased in response to improved grades and recoveries;
  • Mine production increased by 3% in Africa, 2% in North America and 6% in Oceania but declined by 4% in Asia , 1.5% in South America and 3% in europe.

Refined Production

ICSG in its latest study concludes that world refined production remained unchanged in the first four month of 2019 with primary production (electrolytic and electrowinning) declining by 0.2% and secondary production (from scrap) increasing by 0.5%. The decline in world production was due to:

  • A 33% decrease in Chilean electrolytic refined output due to temporary smelter shutdowns whilst undergoing upgrades to comply with new environmental regulations;
  • A decline of 33% in India’s production that was negatively impacted by the shutdown of Vedanta’s Tuticorin smelter in April 2018;
  • A 23% decrease in Zambian refined output due to power supply interruptions, smelter outages and the introduction on 1st January 2019 of a 5% custom duty on copper concentrate imports;
  • Reduced output in major producing countries including Germany, Japan, Peru and the United States due to smelter maintenance shutdowns.

Refined copper declines during the period were offset by growth in Chinese output and increases in Australia, Brazil, Iran and Poland . These declines during the period were offset by growth in Chinese output and increases in production due to recovery from production constraints in 2018.

ICSG concludes that:

  • World refined copper balance in the first 4 months of 2019 saw a 150,000 deficit;
  • China’s bonded stocks are thought to have increased by 140,000 tonnes, compared with the same period in 2018;
  • Copper stocks held at LME, COMEX and SHFE totalled 417,600 tonnes an increase of 19% over the prior period
  • The average LME price was down 2.7% from the may average

invitation to worakyls concert

One our my favorite artists, Worakyls, will be performing at the Zenith Toulouse Metropole, Toulouse France, Sunday November 10, 2019.  The event opens with Worakyls typical electronic music and finishes with his fusion classic-electronic- jazz orchestra.

You are invited. Go here to book

We will be spending a few days in Toulouse around the event, then driving down to the Pyrenees for 3 days and then up through Bordeau to spend 4 days in Poitiers. Message me if you are coming.