HZL enhances output of lead, zinc, and silver with Metso’s solutions

Addressing recovery and production challenges

HZL had to deal with the issue of fluctuating ore recovery, which is a common challenge in the mining industry these days. And when the companies are trying to improve the recovery of several minerals being mined from one site, the issues get even more challenging and becomes a tall task. Large fluctuations in ore type also make the process even more problematic and expensive.

To achieve better end-product quality, HZL needed to focus on improving their recovery process. This included major investments in RCS flotation cells, Visio Froth™ automation systems and froth pumps. With the new flotation system in place, the company is now achieving more than 89.5% lead and 91.5% zinc recovery with concentrate grades of +55% lead & +51% zinc, respectively. In addition to lead and zinc, the mine is also able to achieve close to 84% recovery for silver, which is a major improvement for the producer. According to HZL, the plants at Sindesar Khurd 2 and 3, where the new flotation cells were installed, are delivering good results and matching the expectations of the company.

In addition, the plant is now operating at a higher capacity than its original design levels. The design capacity was originally 1.5 million tonnes, but the company is now achieving 2 million tonnes per annum and for next year, the aim is to reach 2.1 million tons per annum.

Sindesar Khurd mine also acquired Metso’s MKII 5475 gyratory crusher, which is now used as the primary crusher feeding all three mills, so the entire production is dependent on the crusher’s performance. HZL monitors and obtains real time data on the size of the product that the crusher is producing. With the data, they can adjust in order to control the size of the crushed ore and improve the downstream milling performance.

New flotation cells and automation for improved recovery

Automation is a critical factor for the crusher, with production & sizing easily managed with the help of automated settings. The automatic gap adjustment settings in the crusher proved helpful in delivering consistent size and production to HZL. The RCS flotation cells were also able to deliver the highest results and has helped HZL to enhance recovery & improve gradation. Metso Visiofroth™ has also been installed on their flotation equipment. Visio Forth™ measures parameters such as bubble velocity and size of materials in the tank, in order to monitor the performance of the process.  With the data from the Visio Froth™ tool now available, HZL can predict the cell’s performance and adjust as needed. This allows them to have good control over the level of air injected into the system.

“After the installation of the flotation plant in 2017, the performance is matching our expectations. We are getting very good life from the flotation cells, rotors as well as the stators, so we are very satisfied. With Visio Froth, we can identify changes in the flotation cell very quickly and it enables us to improve the performance. The recovery has increased by 0.5% along with the grade. By maintaining the grade, we can improve the recovery by 0.5%. Its availability is almost 100 percent,” Mr. Khan explains.

Altogether, there are 68 flotation cells installed at SK mines. The company will also be supplying an additional complete set of flotation machines for its Rajpura Dariba mine.

Partnering for performance

The company’s partnership with Metso goes back to 1991 when Rampura Agucha mine was first established. Beyond the equipment, Metso also provides a range of services to HZL to support their production. The relationship has matured over the years and now covers multiple aspects of their mineral processing operations. The Metso installations include, gyratory crushers, cone crushers, mining screens, RCS flotation cells, pumps and Visio Froth cameras along with full-service support from Metso.

“Metso is really working in the true sense as a business partner. The Metso engineers remain in touch with us and will remind us that this spare part needs to be replaced. Whenever we place an order, the Metso team is working to deliver within the best time frame they can. They also help in optimizing the life of the spare parts. If there is something you can change to improve the spare part life, they will provide their valuable input,” Mr. Khan tells.

“Metso believes more in preventive maintenance rather than breakdown maintenance and this is basically to ensure that there is no breakdown situation at the plants. Our people are regularly visiting HZL sites, whether it’s the crushing site or floatation site. It is Metso’s ambition that whenever we supply new plants like floatation or mills, our people are available onsite until the performance parameters are achieved to the satisfaction of our customers and this fact has been verified and seconded by Hindustan Zinc Limited,”

says Mr. Vijay Dhar, VP of Services, Pumps and Mining equipment sales in Metso India. He added, “We have been supplying HZL flotation machines to various locations which have given them better results and profit. For the expansion projects at Rajpura Dariba mines, we will be supplying them column flotation machines for the first time. Along with the flotation columns, Metso will also supply ball mills, stud mills and SAG mills. The SAG and stud mills will be the first ones to be supplied in India.

Looking to the future with tailings management and sustainability

Despite the good results, the company is already working on their newest investments. In the future, they want to replace their tailings dam with a dry stacking plant in Rajasthan, which is considered a water scarce area. About 90% of the company’s treatments are related to tailings.

“We value Hindustan Zinc for trusting in the strength of our mining expertise and the reliability of our equipment. We are looking forward to working on the technological upgrades of their plants, especially in tailings dewatering, which is the main challenge not only for Hindustan Zinc, but for all the global mine operators,” Mr. CM Purohit concludes.

More on HZL

Hindustan Zinc Limited (HZL), founded in 1991, is an Indian multi-metal mining conglomerate that produces lead, zinc and silver and is part of the Vedanta Group. It’s one of the world’s largest and India’s only lead-zinc-silver producer. The company’s mines include Rampura Agucha, Sindesar Khurd, Rajpura Dariba, Zawar and Kayad in Rajasthan, India. HZL is also an important global producer for silver. HZL’s Sindesar Khurd mine is one of their oldest silver mines and a leading producer of silver in India. The Company’s total metal production capacities currently stand at 843,000 tonne of Zinc, 201,000 tonnes per annum of Lead and 600 tonnes of Silver, which are all being de-bottlenecked to achieve smelting capacity of 1.2 million tonne per annum. Apart from their main business of mining, HZL is also engaged in wind power and other energy sectors.