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TRANSFORMING TRANSFORMING TRANSFORMING
SUSTAINABILITY REPORT FY 2023 COMMUNITIES THE PLANET THE WORKPLACE

Pilot on red mud utilization raises hopes for carbon-light road construction Sustainable sodium sulphate management helps in cost reduction and waste valorization

Utilizing the waste that we produce, construction material and structural filler, Hindustan Zinc Limited (HZL) is the country’s internally generated Na SO salts now opened up
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which varies from low to high levels was explored. The study has been largest zinc producer and operates several large a whole new vista of opportunity as they could be
of toxicity, in a manner that is completed and further evaluation is smelters. The zinc production process consists used as a replacement for the commercially
productive and with neutral impact awaited. of various stages and different techniques are procured ones. The substitution would not only
on the environment, is an ongoing used as per the output desired. Roasting and help to cut down on operational costs, it would
priority for us. We regularly If pilot trials prove successful, the leaching are two constituent processes of zinc significantly further the waste-to-wealth objective
collaborate with institutions and potential for utilization of red mud in road production, with the removal of iron being an that underpins every aspect of our manufacturing
organizations that are working on construction could reach 1.5 MMT per essential part of the production cycle. The operations. Another crucial advantage was the
allied objectives. Bayer process, year. This would not only address the jarosite process is the most widely used route for substantial reduction in hazardous waste storage
which is used for refining bauxite to environmental issues associated with removing iron elements from zinc, and it is and maintenance costs. The prospect of
produce alumina, generates red mud accumulation but also provide a deployed in our smelters, with jarosite emerging substituting the commercial procured Na SO
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approximately 3 million metric sustainable alternative for road as the waste byproduct. Our 92000 crystals with the internally generated ones carried
tonnes (MMT) of red mud annually, construction materials. Achieving the tonnes-smelter at Debari, near Udaipur in a potential for 50% replacement, which meant a
posing a significant environmental nation’s growth ambitions in a Rajasthan, is a hydrometallurgical zinc smelter sharp increase in the internal production of these
hazard in terms of soil and water carbon-neutral way is essential if India is and produces High Grade (HG) zinc. In FY salts. This would parallelly reduce the volume of
toxicity. Additionally, at our sites to meet its Net Zero commitments and 2022-23, this plant faced a problem as it hazardous waste that we are liable to manage,
there is pre-existing accumulation of through our ‘Transforming Together’ witnessed a cost escalation in the zinc sulfide handle and store as per Hazardous Waste
around 20 MMT of red mud, which focus we are collaborating in making this detector (ZSD) process due to the rising prices Management Rules, 2016. Clearly there were
further exacerbates the possible. of commercial sodium sulphate (Na SO ) which several high-impact gains that would originate
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environmental risk. was used in the Jarosite precipitation stage. The from this waste valorization initiative.
ZSD plant uses nearly 12 -13 MT/day of Na SO .
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Meanwhile for construction of roads, Clearly, a cost-effective alternative had to be The following steps were involved before a
materials like soil and aggregate found else profitability would be significantly full-fledged transition to in-house Na SO
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materials are traditionally used. Due affected. crystals-based Jarosite precipitation could be
to the high demand for such done.
materials from the construction Though the challenge pertained to operating • First, a study was conducted to assess the
sector, soil and its aggregates are costs, the Plant Operations team decided to take quality of the internally produced Na SO
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now severely depleted, and there is a a comprehensive approach that would address crystals and their suitability for use in the
need for finding viable alternatives. other priorities too. The Debari smelter has a Jarosite precipitation process.
To address these different 3000 KLD Zero Liquid Discharge plant for
challenges, Vedanta was recently treatment of effluents. The ZLD plant helps to • Next, experimental trials were carried out to
involved in a laboratory-scale study meet our zero-waste objective. Further, the verify the efficacy of Jarosite precipitation with
conducted by the CSIR-CRRI sludge generated from the treatment goes these crystals.
(Central Road Research Institute) through a crystallization process, and Na SO • Plant trials were then initiated to validate the
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under which the potential application crystals are generated as a byproduct. These findings on a larger scale.
of red mud as an alternative

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