Acid Leaching – Copper Ore Treatment Method

The treatment of copper ores, both oxides and sulfides by means of flotation, hydrometallurgy or other processes has been well established for many years. Flotation has been applied generally to the treatment of sulfide ores, both in small and large scale operations.

Hydrometallurgical methods alone or in combination with flotation have mainly been applied to large tonnage operations to recover copper from low grade native copper, oxidized, or mixed oxide and sulfide ores that are not readily concentrated by flotation alone or by other means, either due to treatment costs or low recovery. The treatment of smaller tonnages of such ores by hydrometallurgy has not been widely employed due to high capital plant costs.

Acid Leaching Process Flowsheet

The method of dissolution by sulfuric acid and ferric sulfate with chemical precipitation by means of scrap or sponge iron appears to offer the best potential for wide application and low costs. Its basic chemistry is not complex but its economic application is dependent on handling of materials and solutions by such procedures to insure low operating costs.

The flowsheet discussed in this study is for treatment of 100 tons per day oxide-sulfide copper ore by the leaching process using sulfuric acid-ferric sulfate solvent. This flowsheet ….Read more

Copper Ore Heap Leaching Agglomeration

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How is Copper Ore Processed


In 1948 Trefoil was privileged to publish an Engineering Notebook Bulletin on Development and Pilot Plant Operations at the Nchanga Consolidated Copper Mines Ltd., Chingola, Northern Rhodesia. This article was authored by Mr. H. L. Talbot, then Consulting Metallurgist to the Anglo-American Group of Companies in Northern Rhodesia.

It is now our privilege to bring our readers up-to-date with a 1962 description of the Concentrator Plant operations.

Since the first article appeared in Trefoil a new concept in the treatment of the copper minerals, oxides and sulphides has been brought about through the progressive research of the Metallurgical Staff of the Concentrator Department.


Much of the history of the development of Nchanga Consolidated Copper Mines Ltd. has been published in the Mining and Metallurgical technical press and it is sufficient, therefore, only to mention the fact that this mine is located on the Northern Rhodesian Copperbelt and is the largest single producer of copper in the British Commonwealth and second only to the Chu- quicamata Mine of Chile Exploration Co., which is the world’s biggest single producer.


The orebodies occur within certain stratigraphic horizons of the Lower Bwana Mkubwa series of sedimentary rocks which rest unconformably ….Read more

Flotation Uranium bearing Copper ore

Uraninite and masuyite are the major uranium minerals, essentially fine grained, in the ores studied. Over 40% of the uranium is distributed in the -8µm fractions compared with copper, which is concentrated mainly in the +8-20µm range. Uranium is concentrated mainly in the copper ore zones, with only marginal levels in the gold-only ores. Poor liberation (due to association with copper sulphides) and entrainment are the major factors identified, which should contribute to uranium recovery in the concentrate.  In this study, approximately 60% of the total uranium was recovered due to association with copper sulphides whilst 40% was via entrainment. Minimizing entrainment of liberated fine uranium particles is crucial to reduce concentrate  uranium grade. Strategies such as effective froth washing and careful consideration of flotation cell hydrodynamics would be required to optimize fine U rejection.

Petrographic examinations of  the ore had indicated  the  impracticability  of  attempting  to concentrate the uranium by floating individual grains of  uraninite. Liberation  of  the  uraninite required grinding to  sizes below  those  suitable for  flotation. However,  there  was  preferential  association  of  the uraninite  with  some  minerals while  others were free of  uraninite  attachment. The  approach to  the development  of  a flotation process was,  therefore, based  upon  an attempt ….Read more

Segregation Process of Mixed Sulphide Copper Ore

Sulphide copper ores are normally concentrated by flotation while the oxide ores undergo hydrometallurgical treatments. The mixed sulphide-oxide copper ores may be processed by combined methods such as flotation followed by leaching and precipitation of the oxidized portion, or vice-versa. Also a Leach-Precipitation-Float Process (LPF Process) has been successfully applied.

However, when oxide or mixed ores have calcareous gangue and acid consumption is too high, sulphidization or ammonium leach have to be applied. When these fail to give simple and economical solutions, no metallurgical alternatives are left. This is the case when the Segregation Process provides new possibilities, since both oxide and mixed ores with or without calcareous gangue can be economically processed and reasonable recoveries of accompanying gold and silver obtained. As it is known, in standard hydrometallurgical treatment of copper ores, silver and gold values are generally lost.Flowsheet on the Segregation Process

The Flowsheet

A typical flowsheet for this process calls for three- stage crushing of original ore to a minus 10 mesh product; mixing of crushed ore with small quantities of common salt and fine coke and roasting of this mixture in a kiln at 750°C in a controlled atmosphere. ….Read more

LPF Process Metallurgical Testing


  1. A Metallurgical Laboratory had completed preliminary economic studies on various processing options applicable to the Minerals Project in South America, containing oxide, transition and sulfide ore reserves. These included heap leaching with SX-EW; use of Roast-Leach-EW of sulfide concentrates to produce CuSO4 crystals; and potential application of the Leach-Precipitation-Flotation (LPF) option to treat all the three ores from Deposit. The results of the above studies indicated that the potential use of LPF provided the best preliminary economics.
  2. Based on the above premise, Minerals authorized Metallurgical Testing Laboratory to undertake an in depth study to confirm the practical and economic viability of the proposed LPF process for treating the ores under a two-phased project.
  3. The results of the initial H2SO4 consumption tests under Phase I of the project indicated that while the amount of acid required for oxide and transition ores were reasonable (94.6 lbs/ton and 155.2 lbs/ton respectively) the acid consumption for sulfide ore was very high (588.6 lbs/ton). Based on this fact, it was jointly (Metallurgical Testing Laboratory) decided to exclude the sulfide ores from the proposed LPF process. Thus, the sulfide ores will be treated by the conventional sulfide flotation process as planned.
  4. The first step in ….Read more

Copper Flotation

Although basic porphyry copper flotation and metallurgy has remained virtually the same for many years, the processing equipment as well as design of the mills has continually been improved to increase production while reducing operating and maintenance costs. Also, considerable attention is paid to automatic sensing devices and automatic controls in order to assure maximum metallurgy and production at all times. For simplicity in this study most of these controls are not shown. Many of the porphyry copper deposits contain molybdenite and some also contain lead and zinc minerals.

Even though these minerals occur in relatively small amounts they can often be economically recovered as by-products for the expense of mining, crushing, and grinding is absorbed in recovery of the copper.Porphyry Copper Flotation

A Copper Flotation Flowsheet

Because the copper in this type of ore usually assays only plus or minus 1% copper, the porphyry copper operations must be relatively large in order to be commercial. The flowsheet in this study illustrates a typical 3,000 ton per day operation. In general most operations of this type have two or more parallel grinding and flotation circuits. For additional capacity, additional parallel ….Read more

Copper LPF Leach Precipitation and Flotation Process

The LPF process is uses for treatment of copper ores in which part or all of the copper occurs in oxidized form presents a problem for recovery. Sulphidization of the oxidized copper minerals using sodium sulphide or sodium sulphydrate is sometimes effective to render the minerals floatable, but generally sulphidization techniques produce low recoveries. Many oxidized copper ores do not react to sulphidization and other means must be used.

What is the LPF Flowsheet

The flowsheet in this study was designed to treat a semi-oxidized ore in which the oxidized (non-sulphide) copper minerals are predominantly chrysocolla and malachite with the sulphide copper meneral being mainly chalcopyrite. The gangue is siliceous so no excessive acid-consuming carbonate gangue minerals are present. Approximately 40% of the total copper occurs in non-sulphide form.Leach - Precipitation - Flotation

Metallurgical tests conducted on the ore showed that sulphidization was ineffective to recover a significant part of the oxidized copper. However, the leach- precipitation-flotation process, commonly referred to as LPF, was shown to be economically feasible. Basically, the L-P-F process consists of dissolving the oxidized copper minerals with sulphuric acid and precipitating the copper as a metallic sponge which responds to flotation. ….Read more

Molybdenum Ore Processing by Flotation

This molybdenum flotation circuit, based on 250-500 tons per 24 hours is designed for low-grade molybdenum ore having high-grade streaks and with pyrite-quartz gangue. It is also basically sound for many other friable sulphide ores, such as antimony, silver and even some lead ores.

The basic ideas stressed in this moly flotation flowsheet are the importance of simplicity and the quick removal of the freed mineral. Gravity flow is used as much as possible in handling the ore and pulp.

The ability of the “Sub-A” Flotation Circuit to produce a high grade concentrate and also to circulate middling products by gravity are important features.

Overgrinding and colloiding the ore, which is so serious in molybdenum flotation is not only expensive but also requires more equipment, such as larger ball mills and cleaner flotation cells and thickener.

Molybdenum Ore Processing by Flotation

The Molybdenum Process Flowsheet

In the crushing department, which is designed for 8-hour per day operation, a heavy duty apron feeder, with plenty of length for picking purposes, starts the ore on its way. The crusher operator with his assistant can sort out any high grade ore, waste rock and wood or tramp iron. Open circuit crushing provides simplicity, low ….Read more

How to Process Copper Lead Zinc Ore with Gold and Silver by Flotation

The flowsheet in this study was designed to treat 500 tons per day of a complex base metal ore containing gold and silver values. The presence of free gold offers opportunity to recover these values in the grinding circuit so that the gold could be amalgamated, and marketed directly to the mint. The ore as mined is very wet and sticky and presents certain handling problems.

The Lead Zinc Copper Flotation and Separation Circuit

Lead-Zinc-Copper-Gold and Silver Flowsheet

Every effort is made to recover the minerals as soon as free. Over-grinding causes slime losses which are both unnecessary and costly. The flowsheet is designed for a compact mill of a size that provides economical treatment at this tonnage.

Crushing Plant

The wet ore is delivered to the coarse ore bin directly from the mine and dumped through a grizzly to prevent any large rocks from lodging in the bin and causing subsequent problems in feeding the crusher. The stored coarse ore is crushed in two stages to produce a ¾-inch product. The reciprocating feeder, overhead eccentric-type jaw crusher, and oversize vibrating screen were selected to alleviate problems in handling a wet and sticky ore. All chutes and transfer points ….Read more

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