Iraqi Geological Journal

Abstract


Introduction
Studies of karst (in general) or limestone (in particular) have been of interest to many geologists (Derek and Paul, 2007;Alobadi et al., 2021;Thinh et al., 2022;Institute of Geology and Minerals, 2005).Vietnam has a carbonate rock distribution area, accounting for about 20% of the territory.The carbonate rock resources are inside in karst regions.The distribution area of carbonate rocks is mainly concentrated in the north and north-central region.The south only has Ha Tien, Kien Giang province (Fig. 1).
Carbonate rocks in Vietnam are mostly found in Dong Giao formations, and Bac Son formations.Their age is Triassic and Carbon-Permian.There are many karst studies in Vietnam.But studies only focus on areas such as karst geology (Tuan, 2004;Tuyet et.al., 1998), karst hydrogeology (Tuyet et al., 1998), hazards on karst (Tuan, 2009;Tuan, 2019) and characteristics of karst poljes (Tuan, 2009;Tuan, 2019;Tuan, 2020).Only a few studies on Carbonate resources are in Vietnam's Direction of sustainable development (Khien, 2010;Tuan, 1999).The problem of exploiting and processing carbonate resources has received little research attention.The article deals with the waste of carbonate rock resources in Vietnam and towards the rational use of carbonate resources for Sustainable Development.

Data Collection
Collect all the data on karst geology, karst hydrogeology, limestone mines, and carbonate resource use fields.

Field Investigation
We have field investigation and research all the territory of Vietnam.This is the basis for determining the limestone distribution areas (Figs. 3 and 4).

Sampling and Sample Analysis
Limestone samples were featured for different formations in the territory of Vietnam (Table 1).At marble mines, limestone is also sampled and analyzed (Tables 2, 3 and 4).In addition, in the detailed study areas, the samples were taken from limestone layers of different colors to determine the CaO content.

Carbonate Rock Formation Process
Limestones are formed in shallow and warm marine environments.Limestone formation became different layers, at the beginning they are a Strike of horizontal bedding.Then, the activities of Endogenous geologies make the limestone layers deviation, where there is a Strike of vertical bedding or form folds.Some places are homogeneous limestone from top to bottom, called massive limestone (Figs. 5 and 6).

Quality of Carbonate Stone
Limestone in Vietnam is distributed mainly in the north, from latitude 17 to the north (Fig. 1).They are present in many different stratigraphies.Karst rocks in the territory of Vietnam are mainly limestone, marble, and dolomite.Limestone is present in stratigraphies of early, mid, late, and early Proterozoic age, has a thin thickness, and often suffers from metamorphosis.In addition, limestone is also found in Cambri, Silur stratigraphy, and most stratigraphy of the age Devonian, Carbon -Pecmi, and Triassic.The total thickness of limestone in Vietnam is about 5,000m; in which limestone has the middle age of Dong Giao formation (T 2 ađg) and Muon Trai formation (T 2 lmt), up to 2,300m thick (Tuyet et al., 1998).Our studies show that carbonate rocks are distributed in 31 provinces and cities of Vietnam.Most of them are in the provinces of Ha Giang, Cao Bang, Lai Chau-Dien Bien, Son La, Quang Binh, Lang Son, Nghe An, Tuyen Quang, Bac Kan.The best quality limestone is carbon-Permian and Triassic aged limestone (Table 1).The results of our field investigation and sampling at the limestone and marble quarries in Yen Bai, Nghe An, and Ha Tien provinces show that the quality of marble and limestone is very good.Total sample taken at mine marble, mine limestone and in the boreholes was 520 samples.The results of the summary chemical analysis on Tables 2, 3, and 4.     In Vietnam, on karst areas are exploited violently, depriving resources and environmental pollution.Exploited limestone is mainly used as raw material for Cement production, paving roads.In many places, limestone content as high as 98% CaCO3 content, but not classified, and still exploited as building materials.

Marble of Yen Binh, Yen Bai
According to incomplete statistics, up to now, there are hundreds of carbonate quarries under the Ministry of Natural Resources and Environment and licensing provinces.Currently, the Ministry of Natural Resources and Environment licenses 87 carbonate quarries, including 38 marble quarries.The marble mines are mostly in Yen Bai, Nghe An, Bac Kan, Tuyen Quang, and Ha Nam provinces (Figs. 11,12,13 and 14).In Vietnam, the processing of carbonate stone is not popular.Carbonate stone is mainly used in raw materials for the construction industry.Firstly, there must be a strategy for exploiting and processing limestone, serving for sustainable development.Some provinces, including Yen Bai province, have imported equipment from China, India, Germany, the US, and Spain for deep processing.In 2020, the People's Committee of Yen Bai province in cooperation with the Joint Stock Company exploiting and processing minerals Vu Gia has started a factory building and processing Vu Gia marble.To produce products from carbonate stones of different sizes from raw to fine-grained and super smooth.Estimated output is 350,000 tons/year.Products are supplied to the domestic market and exported to foreign markets such as India, China, Italy, and some European countries.
According to the Department of Geology and Minerals of Vietnam, Vietnam currently has about 98 white limestone production and processing in operation (Table 5) (DGMVN).Tuyen Quang 1 5 Ha Nam 1 Products of white marble include Calcium Carbonate (CaCO3) uncoated, coated Calcium Carbonate (CaCO3), Plastic filler (Tactical), light powder CaCO3, Limestone powder (CaO), Quicklime, etcFrom carbonate rock created products for industries such as the glass industry, glass production, Ceramics industry, Plastic industry, rubber, Detergent manufacturing industry, Environmental treatment industry, and Livestock industry.
Limestone products have been used in many different industries.In the construction industry, limestone is used to produce cement.In the paint industry, calcium carbonate accounts for more than 60%.Besides, limestone will help enhance anticorrosion, etc.In the medical industry, limestone is used as a calcium supplement, which acts as a deoxidizer in the industry medicine.Limestone is also capable of absorbing gases such as NH3, H2S, CO2, etc. cleaning the water environment, whitening porcelain, making chalk for school use, etc.
One of the best enterprise processing products from carbonate stone in Vietnam is the joint-stock company Yabashi Holdings.From carbonate stone, Yabashi Holdings processed the following products (Table 6): Limestone / Crushed Stone we mine limestone of good quality in the method of bench cut mining by throwing stones into a vertical shaft.Uses: the raw material of quick lime / raw material of calcium carbonate / auxiliary raw material of iron manufacture/aggregate for civil engineering White limestone is manufactured by crushing and grinding and screening limestone of high whiteness yielded in Vietnam.It is used in the chemical field such as paper making.These days it is receiving a lot of attention that it is expected to have the effect to increase the power generation of solar power.Uses: paper making / solar power / For gardening Heavy Calcium Carbonate (Granule)The Limestone is dried and sorted to adjust granule size according to different usages 0.3-1.0mm、1.0-3.0mm、4.0-6.0mm Uses: Basicity adjustment for slug / Fluorine gas adsorption / Fluidised bed boiler / Animal Heavy Calcium Carbonate(Powder)It is manufactured by crushing and screening limestone.We can produce various sizes of particles from superfine ground products to granular products to adapt to various use.It is mainly used for rubber, resin, and paint.Uses: paper making / rubber ・ resin / paint / glass / asphalt / flu gas desulfurization / steel manufacture / fertilizer Quick Limestone(Lump)This product has very few impurities and you can choose grain size and reactivity freely.We are especially good at quick lime with high reactivity.
Uses: Pig iron and iron manufacturing / paper/ pulp / general chemistry industry / civil engineering / desiccant / the quality of water and bottom material improvement / fertilizer Quick Limestone (Powder) The main component of this product is calcium oxide (CaO) and it is a white powder.Limestone mined from the mine is washed with water and screened.And after that quick lime is produced by burning limestone at a high temperature of over 1000 ℃ in the kiln.Uses: pig iron and iron manufacturing / paper/ pulp / general chemistry industry / civil engineering / desiccant / the quality of water and bottom material improvement / fertilizer Slaked Limestone It is used mainly in the neutralization of acids, for example, the neutralization of exhaust gas and wastewater.
Uses: garbage incinerator / exhaust desulfurization / waste water treatment / treatment of fresh water and sewage / civil engineering / fertilizer Slaked Lime(Slurry)It is used to neutralize the acidic waste solution and we can adjust the concentration to fit your needs Uses: Waste Water neutralization / General chemical industry usage/Semiconductors MICROSTAR T slaked lime slaked lime fine powder of high purity produced from carefully selected limestone having very little impurity.It conforms to JIS K8575 special grade reagent and food additives standards.Particle size 325mesh (45μm) nothing left behind.Uses: reagent / industrial use High reactive slaked lime is the slaked lime with increased specific surface area and pore volume more than "JIS special grade slaked lime" to improve drastically reactivity.Its improved flow ability can reduce troubles in silo and transport systems.Uses: garbage incinerator Precipitated Calcium carbonate is synthesized by reacting slaked lime slurry with carbon oxide gas.The product with high whiteness or products with various particle shape which is suitable for each user will be manufactured by changing its synthesis method variously.We have slurry products and powder products and they are used in various fields such as paper making etc.We are only one production plant of precipitated calcium carbonate in the Chubu Region.Uses: paper making / rubber・resin / paint / food additives Precipitated Calcium Carbonate (Slurry) "Choral bright" is synthesized fine precipitated calcium carbonate in high conc.slurry form.(High whiteness, high gloss, low viscosity) Maximum solid 70% Uses: Papermaking/ paint CALSIP lime-based desulfurizing agent for refining is manufactured by various quick lime mixing with auxiliary raw materials (AI ash, Sic, and Si, etc.), and it has powder type, granular type, and briquette type.We manufacture various components and various kinds of refining agents to deal with customers' needs.It is used for the improvement of refining ability and the reduction of refining time.In recent years, it has come to be used for refining without fluorine as the replacement of fluorite.
Uses: steel manufacture / cast iron THREAD LIME lime-based fixation agent is a fixation agent to adapt to the nature of the target soil by mixing various lime and auxiliary raw material.Especially it is effective in the improvement of soft ground.It is a natural material, so it is an environment-friendly product.We have a powdery product, dust proof powder product, and briquette product, and it is used in the construction and civil engineering field.Uses: improvement of soft ground/road works / residential land development/foundation work of railways, airports, buildings / surplus soil recycle Geolime Geolime is developed by Yabashi's original lime-based solidifying agent added to the soil that is extracted upon mining limestone to use the soil as a recycled resource.Uses: Landscaping material for factories, residential areas and other facilities Calsand The product's main ingredient is crushed limestone in which the particle distribution has been adjusted to use as the paving material.Uses: Paving material for ground, parks, and other multi-purposed plaza Processing and using carbonate stones (in general), and marble (in particular) in Vietnam have not achieved high efficiency, causing waste of resources.Compare with Fig. 15 (Foundations of Mendip (British Geological Survey) -Stone as a resource).We see the role of carbonate resources is very large, but in Vietnam, it has not been fully utilized.

Reasonable Use of Carbonate Stone Resources for Sustainable Development
To develop karst areas in Vietnam, it is necessary to have a detailed plan, which delineates the mining areas, the limestone, and marble processing areas for socio-economic development; and forbidden area to preserve geological heritage, environment, landscape, or serve national security and defense etc.
Limestone is a nonrenewable resource.Therefore, we must use it economically, and reasonably, to serve the national sustainable development.Here are some suggestions:

Exploiting Problem
First of all, it is necessary to plan and zone for carbonate mining, including zoning for quality limestone.Mining technology must be improved to minimize resource loss and environmental pollution.

Processing Problem
Vietnam must import the advanced carbonate stone processing technology.The non-executing business will be forbidded.The goal is deep processing, creating competitive products with the market, increasing the number of carbonate stone processing factories to meet market demand.

Environment Protection Problem
The environment in the exploitation and processing areas of limestone carbonate is polluted.The pollutions that are easy to see are noise and dust (Figs. 16 and 17).Problems such as smoke, dust, noise, water pollution, and soil pollution need to be addressed soon in the exploitation and processing of carbonate rocks in Vietnam.

Conclusions
Carbonate resources are nonrenewable resources, Vietnam needs to have plans for zoning exploitation areas, prohibited zones for Sustainable Development.The use of raw materials needs to be minimized, and deep processing of limestone and marble minerals should be prioritized.The urgent requirement now is to change limestone exploiting and processing technology in Vietnam as soon as possible.Adopting advanced technology to exploit and process limestone in Vietnam not only increases the value of processed products of limestone but also contributes to the environmental protection, resources preservation, and sustainable Development of the country.

Fig. 1 .
Fig. 1.Map of karst regions in Vietnam (Institute of Geology and Minerals.2005)

Fig. 2 .
Fig. 2. Determined Karst rock and no karst rock on the satellite image

Fig 3 .
Fig 3. Field investigation in Son La province Fig 4. Bedding of limestone Donggiao formations

Fig 6 .
Fig 6.The massive limestones have aged Carbon-Permian in Ha Long Bay, Quang Ninh province.

Fig 9 .
Fig 9.The limestone blocks are flattened Fig. 10.National scenic spots Kemtrong in being exploited for construction stone

Fig. 11 .
Fig. 11.Illegally quarrying up to Marble thousands of m 3 in Chau Loc commune, Quy Hop district, Nghean province

Fig. 15 .
Fig. 15.Foundations of Mendip (British Geological Survey)stone as a resource

Fig 16 .
Fig 16.Limestone exploitation in Ha Nam province Fig 17.Limestone processing in Ha Nam province

Table 1 .
Results of the analysis of the chemical composition of limestone in Vietnam

Table 2 .
Synthesis of chemical analysis results of marble in Yen Binh, Yen Bai

Table 3 .
Synthesis of chemical analysis results of marble in Chau Cuong-Nghe An

Table 4 .
Synthesis of chemical analysis results of limestone of Hà tien-Kienggiang Places recognized as geological heritage must be protected, this is the prohibited zone.However, in Cam Pha district, Quang Ninh province, lying next to Ha Long city is the place where UNESCO is the world's heritage workers, but the limestone quarries are still being exploited(Figs.7and 8) 3.6.Exploiting Carbonate StoneProvinces with many active carbonate quarries are Ha Nam, Yen Bai, Nghe An, Ninh Binh, etc.

Table 5 .
White limestone processing facilities in Vietnam

Table 6 .
Products processed from carbonate stone of Yabashi Holdings Joint Stock Company