TechNews September 2016 Dedicated to the art and science of Mining Minerals technology

Transcription

1 TechNews September 2016 Dedicated to the art and science of Mining Minerals technology

2 Inside 02

3 Welcome letter 03 Letter from Mining Solutions Have metals prices hit their lowest point? Even though the toughest moment of this commodity downturn may have passed, mining operations still face the challenge of improving their competitive situation and various South American countries have been intensifying their efforts to attract new investment. Low ore prices have led to delays of new projects and after ten years of booming copper prices, the current situation in South America is driving industry players to increase their efforts in the search for alternatives to improve productivity. It is expected that these efforts will leverage their competitive position within the global market, driving profitable growth when ore prices recover. Copper hydrometallurgical operations in particular, which are struggling with water scarcity and refractory ores, have started to use sea water as a main water source and have explored new leach technologies. We invite you to read about our latest research supporting this endeavor and hope to a valuable insight into our findings with regard to the chemical behavior of solvent extraction processes in sulphate-chloride media. In this challenging industry environment, we rely on continuous mutual cooperation with our customers as the way to achieve successful outcomes. Best regards, Felipe Schneider Regional Business Management Mining Solutions South America

4 Dewatering and immobilization of mineral slurries 04 Rheomax ETD technology, a laboratory study of application performance and associated geotechnical characteristics for polymer-assisted tailings deposition of Oil Sands MFT Rheomax ETD technology is based upon the application of a family of polymer chemistries developed by BASF for the mining industry; with the objective to enhance the dewatering and immobilisation of mineral slurries during hydraulic deposition. The laboratory study is focused on Oil Sands Mature Fine Tailings (MFT), investigating the influence of polymer chemistry, dose and conditioning time on the behavioral characteristics of polymer-treated deposits. Subsequent geotechnical characterization of the polymer-treated deposits provides an alternative means by which to investigate the relative effectiveness of each polymer treatment under a number of potential process conditions. This paper reports on the findings of the investigation. Dried deposit performance of tailings in the tailings storage facilities. Field trials provide the ultimate proof of success for any treatment technology, but they are typically time consuming and can be very expensive. Alternatively, laboratory investigation and numerical modelling technics can be used to screen several possible polymer chemistries and identify the most promising options, which are then verified in full scale field trials. This paper describes such a laboratory testing program and the associated modelling efforts. Several polymer chemistries are first evaluated for optimal dosage and conditioning. The evaluation parameters include the net water release and yield stress achieved for each chemistry. The consolidation characteristics of these sam- ples are then determined in the Seepage Induced Consolidation Test. The characteristics consist of void ratio - effective stress (compressibility) relationships and void ratio hydraulic conductivity (permeability) relationships. These relationships are then used in modelling the consolidation process of tailings treated with three different polymer chemistries upon deposition. Three deposition scenarios were evaluated: a thin lift (1 m thick), thick lift (10 m thick) and a deep pour (50 m deep). Cumulative water release with time for each case is normalized with respect to the maximum water release of an untreated material in a deep pour configuration. The comparison of these results provides a rational base for the evaluation of the three polymer chemistries and disposal scenarios. INTRODUCTION Tailings pond The goal of polymer treatment of Oil Sands Mature Fine Tailings is to improve tailings performance upon deposition in tailings storage facilities. The performance parameters of interest include early dewatering of the tailings in order to improve water recovery and reuse in mining operations, reduction of storage volume and shear strength increase to facilitate land reclamation. It is desirable to optimize polymer chemistry and dosage to achieve the most beneficial

5 Elevator talk 05 The new Global Center of Excellence in Tucson, USA This 17,000 sq. ft. facility is designed and built to house 25 technical staff in addition to sales, marketing, technicians and support staff. Its purpose is to support the global mining industry. The main areas of expertise are Technical Services and Research & Development for Solvent Extraction (SX) and Solid Liquid Separation (SLS). The facility is a relocation and expansion of two BASF solvent extraction laboratories in Tucson, USA and the team will continue to support the mining industry around the world, as it has for over 30 years. Jack Bender, Global Development Solvent Extraction Mining Solutions, led the effort to build the new facility and answered our questions: Why did BASF invest in a new facility in Tucson? JB: BASF determined that a new facility was needed to bring more innovation and technical service to SX & SLS customers, both regionally and globally. This expansion allows us to create a modern capabilities facility suited to large scale work, which in turns helps us provide a better service to our customers. In addition, we have started joint research programs with customers that required added capabilities. How does your laboratory differentiate itself? JB: Our lab has purchased new equipment (i.e. GC/FTIR, Titrimetry, ICP, AA organic and aqueous, PSD, HPLC, tensiometry, microscopy, particle size distribution). To maintain BASF s tradition of excellence, we have developed our technical service to use analytical instrumentation to ensure the most accurate analysis of customer samples. The state-of-the-art lab has been expanded from 3,000 sq. ft. to 8,500 sq. ft. The new Global Center of Excellence in Tucson, USA Describe your technical staff JB: Our staff is divided into Analytical, managed by Christopher Hattan, and Innovation, managed by Lauren Hight, while overall lab services are managed by Noah Oliver. Each individual platform is staffed with chemists and engineers who have extensive industry knowledge. Do you have a training program? JB: With the move to the new facility, we have the opportunity to implement a training system where people cross-train across different platforms. We have created a cross-training matrix that includes BASF internal and standard chemical procedures. In addition, we provide field training out of this office including pilot testing and customer support. Furthermore, the additional space at the new site affords us the opportunity to train customers on BASF technologies and to carry out joint projects with customers and engineering firms. Describe your quality program JB: We are committed to providing products and services that add value to our customers offerings and to their downstream applications. To meet this goal, we have integrated quality management principles into our business practices and into our day-to-day activities. Quality is the responsibility of all employees. Our goal is to involve everyone in the continuous improvement of our processes and systems. We constantly strive to improve effectiveness and efficiency, sharing best practices, eliminating barriers and fostering teamwork to meet the ultimate goal of customer satisfaction.

6 Solutions for solvent extraction 06 Solvent Extraction in sulphate-chloride media SCOPE In Chile and Peru, copper hydrometallurgical operations at present face the following challenges: water source scarcity and more refractory ores than in the past, including copper secondary and primary sulfides. The use of sea water as a principal water source and the implementation of new leach technologies using chloride salt addition are increasing in current operations and in new projects. This means leach solutions for solvent extraction will have higher contents of chloride than currently. The chemical behavior of the solvent extraction process has not been adequately studied for sulphate and chloride media. The results of BASF s study involving PLS (pregnant leach solution) with sulphate-chloride and low ph are presented below. Copper production, mt/y Operations with high chloride in PLS (%) Copper production Operations with high chloride in PLS (%) Figure 1. Copper cathode and high chloride in PLS (BASF estimations) INTRODUCTION At present, water in the Chilean mining processes is scarce and the use of the sea water will be a relevant future source. Cochilco s projection of sea water as a principal source to the Chilean mining industry (1) will reach approximately 50% by (Cochilco, the Chiliean Copper Commission advises the Chilean government on matters concerning the production of copper, copper byproducts, metals and industrial mining minerals, except coal and fuels). In the particular case of the hydrometallurgical operations in Chile and Peru, BASF s projection of copper production by SX-EW (solvent extraction-electrowinning), is relatively flat until 2020, when this production is expected to start to decrease from 2.0 mt/y in 2016 to 1.5 mt/y in By 2020, it is expected that 30% of the operations will process high chloride PLS (>45 gpl). Figure 1 describes both trends as indicated.

7 Solutions for solvent extraction 07 The hydrometalurgical future is facing a number of different challenges, such as how to fulfill the actual production capacity of SX-EW, and which will be the best leaching technologies to do it: ROM leach, concentrate leach, white metal leach or in situ leach. Leaching in chloride media is a very promising technology. When a plant process PLS with high chloride (>5 gpl), one of the main concerns with respect to the SX-EW is sufficient control over the chloride transfer to the electrolyte. This is important in order to avoid corrosion by pitting of the stainless plates (permanent cathodes) in electrowinning. The industry uses devices, such as smart-loaded tanks, coalescers to remove aqueous entrainment in organic and wash stages. The right selection of the extractant is another key factor (entrainment control). Ketoxime reagent, which has lower viscosity than modified aldoxime, is certainly an adequate reagent for this purpose. The oxime s chemical behavior in sulphate media is described in Table 1. Ketoxime has moderate strength, while aldoxime or modified aldoxime are usually stronger. There are only a few studies of the chemical behavior in sulphate and chloride media (2, 3). However, extraction in a chloride matrix is well described in the technical literature and illustrates the advantages and disadvantages (Table 4). Property Ketoxime Aldoxime Non modified blend Modified aldoxime Extractive strenght Moderate Very strong Customized Customized Stripping Very good Poor Customized Customized Cu/Fe selectivity Excellent Excellent Excellent Excellent Extraction kinetics Very good Very fast Very fast Very fast Source: BASF Mining Solutions Redbook (5) Table 1. Chemical behavior of oximes in sulphate media

8 Solutions for solvent extraction 08 LEACHING IN SULPHATE AND CHLORIDE MEDIA Chloride is a strong leaching agent, and leach processes have been developed for sulfide copper ores in high chloride media. These processes add CaCl2 or NaCl and H 2 SO 4 to the curing process. Afterwards, the cured ore is stacked in heaps to be leached after a rest stage. An example of this kind of process is Cupro- Chlor, developed by Antofagasta Minerals S.A. (6). The PLS from this kind of processes can require 40 to 120 g/l of chloride. OBJECTIVE The aim of this study is to understand the chemical behavior of oximes in extraction stages with and without chloride in PLS solution (sulphate and chloride media). Figure 2. Mixed ore: oxide and secondary copper sulfide EXPERIMENTAL PLAN Synthetic PLS was prepared at a laboratory with metal concentrations (Al+3, Mg+2, Fe+3, Fe+2, Mn+2) and adjusted to average conditions in Chilean operations (95 SO 4-2 g/l). Chloride concentrations of 0, 20, 40 and 90 g/l were studied with the addition of NaCl to the PLS. Furthermore, the ph was adjusted to 1.5 and 1.0 by the addition of H 2 SO 4. Solution PLS Cl- g/l SO42- g/l ph PLS 1 A ,0 PLS 2 A ,5 PLS 3 B ,0 PLS 4 B ,5 PLS 5 C ,0 PLS 6 C ,5 PLS 7 D ,0 PLS 8 D ,5 Table 2. PLS solutions The organic phase was prepared with Orfom SX 80 diluent and BASF extractants based on ketoxime (LIX 84I) and modified aldoxime (LIX 684N-LV), adjusted to 24% v/v. Lean electrolyte (LE) was prepared containing 35 g/l Cu and 180 g/l acid (lean electrolyte). The electrolyte was a standard electrolyte. Due to the measures taken by the operations or projects control the chloride transfer to the electrolyte, the electrolyte does not vary significantly with PLS having higher chloride content. STANDARD PERFORMANCE PARAMETERS The standard parameters analyzed were extraction and strip isotherms, which provide a metallurgical performance approach and extraction kinetic tests for an approach to the expected industrial mixing efficiency. Isotherms and kinetics testing were perform for each PLS solution as described in Table 2. PLS was contacted with the organic solution prepared at 24% v/v (LIX 84I or LIX 684N-LV). All tests were performed according to the BASF s standard procedures. The chemical characterization of PLS is summarized in Table 3. Ion Unit Value Cu 2+ g/l 4,5 SO 42- g/l 95 Cl - g/l 0; 20; 40; 90 Fe T g/l 2 Fe 2+ g/l 0,4 Fe 3+ g/l 1,6 Mn 2+ g/l 2 Al 3+ g/l 6,14 Mg 2+ g/l 11,21 Na + g/l 0 58 ph 1.0 ; 1.5 Table 3. PLS composition

9 Solutions for solvent extraction 09 EXPERIMENTAL RESULTS a) Acid, ph and chloride relationship Higher chloride content implies lower ph, as described in the Figure 4. Therefore, with high chloride, a lower ph is expected: for a sample of 2-4 g/l acid, a ph in the range of is expected, rather than the normal ph registered in most hydrometallurgical operations. In high chloride, the activity coefficient of hydrogen ion changes and modifies the ph. b) Extraction isotherms Laboratory extraction isotherms were performed to study the chemical equilibrium with different levels of chloride at ph 1.5 and 1.0. Figure 4 shows the isotherms at ph 1.0, with and without chloride in the PLS. At higher chloride content and lower ph (ph=1.0), an increase of copper load in the organic was detected. This effect is stronger for the ketoximes reagent than for the modified aldoxime. Table 4 summarizes the results obtained for the ph samples. Figure 3. Acid, ph and chloride content Figure 4. Extraction isotherms ph 1.0 Copper load in organic PLS ph 1.0 g/l Copper load in organic PLS ph 1.5 g/l Solution LIX 84I LIX 684N-LV Solution LIX 84I LIX 684N-LV 90 g/l Cl - 9,5 11,4 90 g/l Cl - 11,2 13,2 0 g/l Cl - 7,1 9,5 0 g/l Cl - 10,6 12,6 Diff. 2,39 1,88 Diff. 0,63 0,6 % increase % increase 6 5 Table 4. Maximum copper loading according to PLS and reagent (Cu g/l)

10 Solutions for solvent extraction 10 c) Stripping isotherms Stripping isotherms were prepared for each reagent tested in order to evaluate the copper extraction in a configuration considering the extraction and stripping behavior in the copper recovery of a SX configuration. Table 5 indicates the strip isotherms for each case. d) Kinetic tests Extraction kinetic tests were conducted for ph 1.5 and ph 1.0 samples with 0 g/l and 90 g/l chloride content. Their results are presented in Figure 5. Even for a PLS without chloride, both reagents have good extraction kinetics considering the mixing time is seconds at industrial operations. With 90 g/l of chloride in the PLS, kinetics improve very similarly for both reagents, ketoxime and modified aldoxime. LIX 84I LIX 684N-LV aq org aq org 37 0, , , , , , , , , , , ,98 Table 5. Strip Isotherms (Cu in g/l) Figure 5. Extraction kinetics PLS ph 1.0 with 0 and 90 Cl- 90 g/l

11 Solutions for solvent extraction 11 e) Circuit evaluation In order to evaluate the metallurgical performance, a configuration of 2E 1S was evaluated using the BASF software ISOCALC to calculate the copper transfer at ph 1.0 when ketoxime or modified aldoxime is used for PLS containing 0 or 90 g/l of chloride. The principal parameters evaluated were copper recovery and copper in the organic (maximum copper load, Cu in stripped organic and Cu in loaded organic). The copper in organic behavior is illustrated in Figure 6. The modified aldoxime can load more copper at a specific ph, but the copper transfer is similar in both cases due to the increased performance of the ketoxime in the strip stage. However, when the chloride content is high (90 g/l), the copper transfer by the ketoxime reagent is higher than that of the modified aldoxime. Figure 6. Copper in organic Table 7 displays an overview of the copper recovery in SX obtained for each condition. Ketoxime performs better than modified aldoxime despite the low ph when the chloride content in the PLS is high, 90 g/l. PLS (g/l) Conc. LE (g/l) Conc. Stream Flow (m 3 /h) SE (%) Cu +2 4,4 Cu PLS 1000 E1 90 SO Acid 180 LE 230 E2 90 Cl Organic 1200 S 95 ph 1 O/A ratio 1,2 Cl - (g/l) LIX 84I LIX 684N-LV 0 76,8 79, ,5 87,2 Diff Table 7. Copper extraction (%) in 2E 1S circuit PLS: Pregnant leach solution, LE: lean electrolyte and SE: stage efficiency Table 6. Circuit conditions

12 Solutions for solvent extraction 12 CONCLUSIONS South American hydrometallurgical operations are expected to experience an increase in the use of sea water and/or the addition of chloride salt to the leaching process in order to improve the leaching performance for refractory and/or secondary sulfide ores. Consequently the PLS will have a higher chloride content than 25 g/l in 30% or 40% of the hydrometallurgical operations. For these conditions, PLS will have a low ph, with values of 1.0 to 1.2. This is a challenge for solvent extraction in terms of copper transfer. However, the higher chloride in PLS improves the chemical behavior of the oximes in extraction stages, increasing the copper load in organic and the extraction kinetics. Ketoximes LIX 84I are a major improvement over modified aldoximes. For a PLS with 4.4 g Cu/L and ph 1.0, the maximum copper load increase is 34%, while modified aldoximes only increase by 20%. The increased performance of ketoxime over modified aldoxime during the strip stage means that ketoxime LIX 841 performs slightly better than modified aldoxime in a conventional circuit with a configuration of 2E 1S and the PLS at ph 1.0. For these conditions (PLS with a high level of chloride and a low ph) the ketokime reagent is an excellent alternative in terms of copper transfer and physical behavior. A positive physical performance is reported in current operations, based on the low viscosity of the reagent and ketoxime without equilibrium modifiers. REFERENCES Montes, C, Water use in copper mining: Trends of a critical input. Chilean Copper Commission, April 2016 ( Lu, J, Dreisenger, D, 2013b. Solvent extraction of copper from chloride solution I-loading isotherm, Hydrometallurgy 137, Lu, J, Dreisenger, D, Solvent extraction of copper from chloride solution II-Cuprous oxidation by oxygen coupled with simultaneous cupric solvent extraction, Hydrometallurgy 138, Szymanowski, J 1993, Hydroxioximes and Copper Hydrometallurgy, CRC Press BASF Mining Solutions Redbook Aroca, F, Backit, A, Jacob, J, CuproChlor a hydrometallurgical technology for mineral sulfide leaching. Minera Michilla, Antofagasta Minerals, Hydroprocess 2012

13 Cooperation with mining universities 13 Future opinion leaders in mining get to know BASF As part of BASF s initiative to strengthen itself, a group of ten Metallurgy students from Curtin University s Western Australian School of Mines (WASM) visited the Ludwigshafen site on July 1st. This is an important target group for BASF s Mining Solutions business because the students are the opinion leaders of the future for the mining industry. In a few years, the participants will hold key positions at customers, said Richard Macoun Segment Manager New Technologies, who initiated the visit. The visit gave the students an insight into BASF and helps to pass on a positive impression. The future metallurgists took part in a guided tour of production sites in Ludwigshafen and the Mining Solutions laboratories to experience BASF s Verbund concept of modern chemicals, advanced research, production equipment, and Responsible Care for the environment. We were very impressed how diverse BASF is. The Visitor Center is one of the best in the world. Since Australia is a mining country, chemicals are essential for us. This visit is a very good opportunity to see how chemicals are produced, said Richard Diaz Alorro, Lecturer at the Department of Mining Engineering and Metallurgical Engineering, WASM. As well as the visit to Ludwigshafen, the students were given a one-day training session on Flocculation, Coagulation and Solid Liquid Separation, conducted by the Mining Technology Group at WASM s Kalgoorlie campus. WASM students and lecturer Richard Diaz Alorro right visiting the Mining Solutions laboratory in Ludwigshafen, Germany. Left: Adran Villanueva, BASF; right: Tamara Kuelzer, BASF BASF Visitor Center

14 Expomin 2016 in Chile 14 BASF at Expomin 2016 Publishing information In April 2016, BASF participated at Expomin 2016, one of the most important mining congresses worldwide. As in previous years, the 14th version of this biannual event was held in Santiago, Chile and was organized by Feria Internacional de Santiago (FISA). Various BASF Divisions presented at the Expomin 2016, Chile A total of 1,266 companies from 35 countries exhibited their products and services at the fair. 49% of the companies were from Chile, while Asia, the USA and Germany were also well represented. This year 70,000 participants visited the event, including 2,000 visitors from abroad. Mining is one of the focus industries for our business strategy, which is why Expomin represents an excellent opportunity to meet the most important market players in the industry. At BASF we create chemistry for sustainable mining operations through innovative solutions for the entire value chain and Expomin is a good venue for technical exchange with our customers, stated Jorge Mejías, Sales Manager, Mining Solutions BASF Chile and Peru. BASF presented solutions for the min- ing industry at its 49-m² stand in the spirit of its slogan We create chemistry for sustainable mining operations. Customers and partners were invited to learn more about the extensive range of products and technologies for mineral processing, construction and maintenance of mining infrastructure, underground mining construction, water treatment and mining equipment. The convention held during Expomin gave all the participants the opportunity to share and exchange technical knowledge under the main slogan of productivity and sustainability. 8,000 participants attended these workshops and presentations. We launched a new brochure, which shows BASF s solutions for the entire mining industry value chain at a single glance, concluded Lena Tiedemann, Regional Marketing Manager Mining Solutions, South America. Printing details Publisher: Authors: Pictures: BASF SE Ludwigshafen Germany Tel: L. Ardiles J. Carranza M. Catling J. Donath H. Kalitzky E. Martinez J. Mejías C. del Río L. Utting H. Yáñez istockphoto Getty Images All other pictures BASF Published: September 2016 Art direction and design: mangler & noller gmbh Dantestraße Heidelberg Germany